Wow.
Sheesh, I make a simple post, go away for the weekend, and what happens? Tons of people read it and post very well-thought replies. Bravo, everyone!
I agreed with a lot of what people said, and it really made me think. I'll try to do justice to the replies, and put in one giant plug for the Viking Berserk, all in one shot:
First, though, I have to point out another limitation (it's not a bug; it's a feature!) of my ranking that wasn't immediately apparent to me: Early on, when I gave each unit an off-the-cuff ranking, I was amazed at how even my distribution was. I took that nice distribution all the way to the bank, and cast all the units in a rock-solid grade distribution that looked like this:
3 A's (one A+)
5 B's (one B+)
8 C's (two C+, two C-)
5 D's (one D-)
3 F's (one F-)
Although this was really cool and I gave myself a nice pat on the back for it, the distribution had a lot of drawbacks. First was the crunch around the C+ area -- there were a lot of units I wanted to give a B to, but couldn't. A full third of the UU's in the game got a C, which sounded like I was blowing them off, but I really wasn't. I just couldn't think of which B unit they would take the place of.
Also, a big thanks to the people who pointed out my factual errors (I said the F-15 couldn't trigger a GA and the War Chariot was made obsolete by researching Horseback Riding). I guess my playing experience failed me -- I was America once and remember specifically trying everything imaginable to trigger a GA with an F-15. Maybe I never fully killed an enemy bomber, and I guess I was never intercepted on a bombing run. (Go figure! I wasn't using my air superiority fighter for bombing missions!

) But, man, I'm the Egyptians in my current game -- you'd think I'd know their upgrade path!
I was going to respond to everyone, but since there were so many replies I'll just hit the biggies...
German Panzer (I gave it a C) -- Man, does it look like I've dropped the ball on this one! In retrospect I think I did underrate it, but it does have a few drawbacks that, in my mind, keep it from being ranked with the elite UU's. First, in just about every game I've played, I've basically either won or lost by the time Tanks come around. The Panzer just comes too late to swing the game either way for me. Second, even if you've beelined for Motorized Transportation, Modern Armor is only five techs away (I'm counting Rocketry), which gives the Panzer a short life span. True, they really do knock the living daylights out of Industrial Era units, but so do Tanks, in my experience (especially if you cut off that rubber supply). I think I did underrate the Panzer, but not by a lot. It's a really cool unit; I just wish the timing were a little better.
Arab Ansar Warrior (I gave it a C+) -- This was a notable casualty of my rock-solid distribution. It's basically a cheaper Rider with one less defensive point, a trade that I feel makes the Ansar Warrior slightly less well off. Since I gave the Rider a B, I gave the Ansar Warrior a C+ -- slightly less than the Rider.
Carthaginian Numidian Mercenary (I gave it a C) -- The plugs by phizuol and others almost made me rethink my position on the Numidian Mercanaries, but then Sullla's post made me stand my ground. Their cost is just too prohibitive for being the only Ancient Era defender. More importantly, though, I argued that they're not as good as either the Legion or the Hoplite, both units that got a B (and the Legion's grade was contested at that). Thus, the Numidian Mercenary gets a C.
Ottoman Sipahi (I gave it a B+) -- Just that little bit of encouragement has pushed me over the edge. The Sipahi should have gotten an A.
Roman Legionary (I gave it a B) -- I always thought the Legionary (I prefer "Legion," too) was overrated by many, and it seems I've overrated it myself! Sullla and Bismarck did a very good job convincing me of this, though I agree with Sirp's assessment: the Legionary is a good unit, but not necessarily deserving of top honors.
Egyptian War Chariot (I gave it a C-) -- This unit is kind of like my anti-Legionary -- I always thought it was underrated, and I've underrated it myself! I wouldn't give this unit more than a C or C+, though, because using War Chariots seems like an all-or-nothing proposition: you either take advantage of their cheap cost and crank them out like crazy, or you scoff at them. Or, like Psychlone, you keep them around for a later GA. I'll take the middle ground on this one, though I certainly see jack merchant and Sirp's pro-Chariot perspective.
Heck, I'm thinking the Mongols might be even worse than the English. At least I don't sit there thinking "I don't want these man-o-wars, give me back my precious frigates!"
All I can say is,
Okay, now for the ultimate plug for the Viking Berserks. And I thought I gave these guys too much attention in my original post...
Viking Berserk (I gave it an A+) -- I won't even talk about what this unit does on a map with a lot of water. Try it just once and tell me with a straight face that the Berserk is not the most insanely overpowered unit in Civ3.
But let's imagine the worst possible scenario for the Viking player: you have no coastal cities. Heck, the whole map is one big block of land, so your opponents don't have any, either. So you're left with a 6-attack, 1 movement shock troop near the beginning of the Middle Ages. Move a few of your favorite defenders or artillery in-step with a stack of Berserks, and what do you have? An Immortal-like advantage over Pikemen (6 attack vs. 3 defense). And as Sirp pointed out, if the enemy has Musket Men, you can choose whether you use Berserks (a la Swordsmen) or Knights (a la Horsemen) to attack. Using one or the other might just be a question of style, but the Berserk is the only unit that even gives you that choice! Remember, Berserks have the same attack as Cavalry and can be researched as fast as Knights! But let's fast forward a bit to the Infantry Era, as I call it, when the best attacking strategy is generally carting around stacks of Artillery and Infantry. Heck, man, throw those Berserks in there, too -- many of them will likely be elite by now, and a bunch of reduced-HP Infantry are like cogs in a Great Leader factory. Keep in mind, this is the absolute worst case scenario for Berserks (in terms of circumstance, not how well the game is going in general). What about the worst case scenario for Persia? No iron = no Immortals! Or what if the Ottomans don't have Saltpeter? Or the Iroquois horses? The Berserk is still a good unit, even if there is no water in sight.
Now let's consider the average scenario: continents and 70% water (or whatever's standard). Sirp hit the nail on the head when he said "without the amphibious assault ability, they really aren't *that* great." He's right -- without it, I would give them a B or so. But with it, an attacking Berserk force is literally invincible. Invincible! Never mind their low movement -- you'll be moving them in ships! Never mind their low defense (which is still higher than the unit they replace, Longbowmen) --
they cannot be attacked. The only vulnerable Berserk is the one that wins the final battle to take the city, and if you want to keep that city and/or Berserk, just unload some defensive units from your ships. You can easily take or pillage every enemy coastal city with Berserks.
Every single one. While this might not utterly destroy a civilization, it will certainly cripple it, and after a few turns of suffering from your incessant raiding parties, your enemy will be more than happy to give you whatever concessions you desire. Go look at any given Civ map (minus, perhaps, the super-pangea ones) and imagine taking every coastal city with minimal casualties. It can be done, easily, with Berserks. Yes, you have to build some ships, but you can plan this from the beginning -- and what better to build in the interim between Map Making and Invention? Other than upgradable Archers, I mean.
Look, there's a reason Marines attack like pansies. The amphibious attack capability is really powerful, and introducing it into the early Middle Ages
and giving that unit a higher attack than any of its contemporaries is just asking for some serious, serious Viking whoop-ass. If somebody had put this unit into a mod, I wouldn't have downloaded it. Well, maybe I would, but only because it's cool...
*phew* I think I'm done for now. I don't really have much to say about all the editing suggestions, so maybe I will get to those later.
Everyone, thanks again for all the thoughtful insights!