(all numbers from normal/standard)
This is a complex thing to study, because the costs and benefits of each technology are not limited to it's straight research cost or benefits handed out. The true cost benefit of a technology are something like:
cost of tech + (cost of each prereq-benefit of each prereq) vs Benefits of tech + (benefits of each tech branching off of this tech - costs of those techs).
These costs and benefits are further modified by playstyle, map types, difficulty, synergy with other techs that aren't acutally required (less need for mages if you have priests, etc.), resource availibility, and personal taste. So: this is inexact and somewhat subjective, comment if you disagree, of course. Oh, and it might end up being long. Also, I'm biased towards minor changes.
Each tech is listed under it's incremental cost (how much is needed if all prereqs are already researched) with the total cost (if you went straight for those techs) in parenthesis.
I'll evaluate each tech for economic and military usefulness, 0-5, relative to others of its costs.
Techs (real cost)
195
Agriculture E3 M1 Everyone needs farms somewhere, and this will also get settlers/workers out quicker. The 1 military rank is from good synergy with conquest.
Crafting E1 M1 Allows one resource, and maybe some

, this is the loser of its peers and serves to push back mining and construction. The M1 is from eventual axemen.
Exploration E4 M3 Vital in and of itself, connecting resources and getting troops around quicker.
Ancient Chants E3 M1-3 Needed for expansion if not creative. Also, orc slaying is vital if playing raging barbs.
T1 conclusion: No changes should be made; it'd penalize civs who start with them.
312 (507)
Animal Husbandry E2-4 M0-1 a gamble economically, depends on map and settings. Captured animals are a possible way to quick happiness if you get lucky, and animal resources are all pretty good.
Calendar E2 M2? A wonder, but building a wonder at this time is risky. Two strategic resources and most of the happy ones, but good luck using either any time soon!
Festivals E2 M0
Mining E3 M2
Masonry E1 M1 Pyramids are gone, walls may be useful. Leads to good places
Cartography E0 M1 Not doing too much by itself.
Fishing E 3 M0 THis is usually useful even if it didn't go anywhere.
Hunting E2, M3 hunters are great if you get them now.
Education E6 M2 Cottages are essential, and apprenticeship is a immediate promotion. Plus, a ton of techs require this
Mysticism E3-4, M0-1, some vital civics and free science
T2 Conclusion: Looking at techs in and of themselves, Education should probably be priced higher, hunting and mysticism as well though less so, and Cartography and masonry reduced in price or else boosted in utility.
468 (1599)
Way of Wicked E0 M0-1
Way of Wise E1 M0-1 Not alot one these by themselves. They're just there to add their price to Order/Veil
624
Horseback Riding (1131) E0 M3 decent unit
Way of Earth (1638) E3-5 M1-2 Bigger boost if you found it, of course, but any religion is worth getting if you can.
Bronze Working (1131) E2-3 M1-5 Axemen are the only unit at this time that can take cities, imo. Need copper of course.
Construction (1131) E1-2 M3 Seige are needed, though seige workshops are pretty expensive imo. Spreading irrigation is useful, usually.
Trade (2261) E5 M3 Double the real price of others at this level, but writing is useful in and of itself. Chariots look great, but need construction and AH too, so they are more expensive than they look. Basically chariots are a reward for not tech specializing. Or for trading techs well.
Sailing (1131) E1-4 M1-3, one of the most map dependant techs. Don't know if tech prices can be adjusted based on amount of water on map?
M. Deep (1638) E3-4, M3 Better units than the other religions in this level, poorer economic benefits. Still good!
Forests (1638) E3-4, M2 nice healthy religion.
Tracking (1131) E0 M1 stepstone for recon.
Archery (1131) E0 M3 safe bet as it needs no resource, no other benifits attached to the tech though.
Code of Laws (1131) E2-3, M0 Needed eventually
Writing (1131) E3-4 M0 Research multiplying is worth the investment, though free tech is unlikely
Knowledge of the Ether (1131) E0-3, M0-3, depends on your mana, of course.
Philosophy (1131) E1, M1 Step stone for all religions
Warfare (2261) E0 M3-4 Expensive as it needs bronze working. Worth it? maybe.
T3 conclusion
Is it possible to give the free tech to the first with writing AND philosophy?
Bronze working >> horseback riding and archery, imo, but if theres no copper
I think perhaps warfare should be an alternative to bronze working rather than requiring it. I don't see it so powerful as to need to be twice the others' costs
unless it's on Axemen anyway!
Tracking is just next to useless. Consider killing it, moving sentry to cartography, and having poison and Animal handling require cartography.
Trade is rightly expensive.
Religion techs could increase their cost w/o losing a drop of desireability too
1248
Drama (2262) E1-3 M1 Vital for cultural win, of course
Smelting (2379) E2 M2 Forges!
Arete (2379) E1 M4-5 If you're runes, grab it first.
Sanitation (2379) E5 M0 clear jungles and increase pop by 3
Honor (2379) E0 M2 Decent national wonder.
Deception (3969) E0 M0-2? Going though changes, but still only useful to the first to research it
Optics (2379) E0-3 M0-2, map dependant, but could give you more room to expand
Mind Stapling (2379) E2-3 M 3-5
Poison (2379) E0 M2-3 Deadend tech, though not unit. Useful if your opponents have the copper monopoly
Animal handling (2886) E0-1 M4 Rangers are very good atm.
Military strat (7254) E0, M2 I don't use this much, don't know why it is so expensive. Surely one could have a strategy without good maces? Perhaps a philosophy prereq
Currency (2379) E4 M2-4 Changes coming here militarily, but the economic benefits are worthwhile even w/o mercs.
Monarcy (2379) E1-3, M1 Possible to remove unhappiness here
Mathematics (2379) E4 M1 ditto currency w/o the mercs
Divination (2379) Not going to consider all the spells atm, any of these are decent picks depending on taste
Alteration (2379)
Elementalism (2379)
Necromancy (2379)
Priesthood (2693) E1 M4 Priests are good. varys by religion
Awaken Ancients (2379) E0 M1 culture warfare and dragon prereq. You'll get it if you can.
T4 Conclusion: Military strategy should require philosophy over iron working. Nothing there is so strong, imo. Currency could use a bit higher price, it seems. Maybe smelting and sanitation too. Honor and deception should be cheaper or better.
2496
Stirrups (3627) E0 M3 Cheapest tech here because of few prereqs. OTOH, you'll probably want the other techs prereqs anyway. I'll have to try these guys more.
Iron working (4875) E2 M4 very good tech. might need slight cost inc.
Medicine (5382) E3 M0-2 A bit overpriced, unless you have runes or are Grigori; unhealth isn't that big a problem at this point.
Astronomy (4875) E1 M? Need to see v16 to judge ships. At least not totally worthless on highland with tower of eyes. Again, can costs be changed based on a maps water content?
Ferral Bond (4875) E0 M0-7 heh, first one here gets a leg up.
Taxation (4875) E3-4 M0 good civic and building
Infernal Pact (5499) E1-4 M3-4 Founder gets more, but needed if you want state religion still pricey
Orders from Heaven (5811) E1-3 M0-4 Hero is nice, for the first, otherwise no military yet. Holy city is good, otherwise just temples. Pricey
Constitution (6279) E3 M0 republic is good, I think. doesn't merit the price atm.
Alchemy (4875) E1-2 M0-2 Don't know quite why the Ai rushes this, but since they do, it's not quite so attractive for the rest of us. could use a lower cost.
Engineering (6006) E1 M4 Road bonus is good for military. Windmills might be needed. Wonder, but not a great one, imo. pricey with prereq
Feudalism (6629) E? M0 Permanent alliances should default to on. Needs a boost or cost decrease unless you're Calabim
Religious Law (5814) E2-3 M0 Comes a bit late, could use a lower cost
Sorcery (5814) E? M? Depends on Mana, but is rarely a bad tech to get soon
Summoning(5814)E? M? Depends on Mana, but is rarely a bad tech to get soon
Fanaticism (7062) E1? M3 Decent units and castles. Monarchy bumps price up quite a bit though
Arcane Lore (12993) E-3-5 M0-2 Hero for OO, towns get hammers mean huge economic boost. Still, the two prereqs means it belongs to the next category as stands.
Animal Mastery (12246) E0 M4 Needed Ironworking means it is really a T6 as well.
T5 conclusion: eh, read each individual tech at this point, prices are fluxuating greatly w/in tiers due to prereqs. Apropriately for arcane lore &AM; less so for constitution and feudalism
4992
Bowyers (7254) E0 M3 Cost should be adjusted down as is. Comprable to macemen, though with a resource lower requirement. 2400 additional beakers to reach than ironworking?
Righteousness (12522) E0 M4-5 Grab quick if you have the order. And paladins look very pretty!
Rage (16929) E0 M4 loses out to religious warriors in this tier due to IW requirement. Reduce rage tech cost
Malevolent Designs (12522) E0 M4
Theology (10806) E0-4 M4 Couple of wonders and a high level caster? Why don't I get this sooner?
Divine Right (10806) E0 M6 Okay, I love Inquisitors. Price this higher.
Soul Debt (10806) E? M0 tech to delay summoners. Interesting wonder, though. slight decrease, but summoners do indeed rock.
Blasting (19743) E0 M3-4 Don't use this much myself; looks overpriced
Liberalism (11271) E4 M-1High due to the WoW req on Constitution. Good civics, I suppose, but becareful not to lose your heroes!
Guilds (9867) E1-3? M 5 heh, increase Cost!! I hate shadows!
Mercantilism (9867) E2-3? M0 Better for Grigori, perhaps a bit expensive though.
Machinery (10998) E3 M3 Good cost, I think. production boosts, but expensive ones, and a great city defender, but national units fare poorer at defense--can't move them around too well.
Commune w/ Nature (12560) E4-6, M4-5 Pricey, but maybe not enough. Druids are strong and versitile. Unless you start in paradise, a priority
Warhorses (7488) E0 M4 A very good unit for this price. Perhaps increase it, though I wasn't expecting to say that.
Metal Casting (9867) E0 M3-? Drydocks good if theres water, But Pikemen aren't top of the line yet, so this may be a bit pricey. Then again, experience says otherwise.
Corruption of Spirit (10491) Gah, speaking of pricey! Really, lower the cost or add some more bonuses.
Unquestioning Obedience (10803) See above. Better free unit, though slightly higher research time
9984
Strength of Will (22977) E? M2-5 depends on mana, but always useful. good price if you have reagents. If not, go kill someone!
Golem Mastery (24108) E0 M2 You'll get it if you founded runes and have sky high production; otherwise? nah
Ethereal Call (20790) E0 M6 Yes, love these guys too. Oh, and Shadows make me
Mithril Working (19860) E0 M1 Pricey, for nothing yet!
Armored Cavalry (37332) E0 M2 Yes that's right, these beautiful units are that freaking expensive. Due the lames requirement. And they are not really much better than War charriots. Reduce price, eleminate Lames requitement, or make knights uber.
Domesticate Camels (29211) E0, M3 weaker than War Charriots, but great withdrawl. expensive.
Lames (19860) E0 M3 Decent national unit, fair price
Celerty (17238)E0 M4 decent cost
Precision (24492)E0 M4 I bit expensive; also, on an unrealated note, how about allowing assassains upgrade to marksmen OR shadows?
14976
Elephants (44187) E0 M4 well, more expensive than knights, but quite strong. I've rarely seen these fellows, though.
Mithril Weapons (34836) E0 M4 good units. Might need them for a few entrenched cities fair price.
Divine Essence (45192) E0 M4-5 Immortals and dragons? okay, I can live with the cost.
Omniscience (50006) E0 M0 Yes, no real benefits here. You're only getting this if there is nothing left or you want to destroy the world.
Pass through ether (35766) E0 M4-5 gates make your units count twice, as they can warp on anywhere.
15600
Armegeddon (73094)
Future x (73094 + 15600x) E2 M0 Why require Armegeddon? Anyone going for armegeddon probably isn't planning for the future!
Okay, that was long. Agree, disagree?
(please forgive typos)