I rewrote some of my settings:
Multiple Production Multiple Research Usable Mountains Assimilation all ON the 4 must haves.
Larger citieson
Limited religionson
No
barb civs (more room)
I like
realistic corporations they are cool, it influences your civic choice coz you want to encourage corporations to come to your nation.
Custom map - Size custom- in between large and huge is what i'd recommend- you'll still need a good computer to run this in modern era but should run well without any slowdown etc.
Snaky continents, hard terrain variation, 6-8 continents with 4 tile seperation (aprox, 12-20 civs i'd recommend for this size). I like No Wrap, makes it kinda more strategic however the AI does better when the world is round.
Great Commanders - although this is a cool option, the AI can't use it very well currently so I turn this off.
Advanced Espionage- OFF i think subverting cities is broken, you still get spy promotions and extra spy missions with this off.
Advanced Diplomacy - This is a good option,
HOWEVER - turn off military unit trading in options coz I think this is unbalanced, also worker trading is ok but basically only put it on if your playing a difficulty level your not confident with coz the AI pays alot of $$$ for your workers and i don't think i've ever purchased one.
Tech Brokering - Not allowed, tech trading off completely is a good way to play but it makes the game too slow for me so this is a nice compromise. Abusing diplomacy so to clinch all the new techs is a fundamental strategy against immortal/deity imo.
Guilds - off
Advanced Nukes off
Unlimited Wonders I like to have this off, however the AI like it on so i let them enjoy it
Modern Corporations off, enough is enough imo.
Start As Minor I don't like this, so off.
Revolutions This is a cool option, however again the AI prefers it off (as in they do better).
Ruthless AI At first I thought this option would be terrible, its actually very important. It was designed to make the AI trade techs with each other WAY more, and the AI also gets much more upset if you trade with people they're at war with as well as some other features. It doesn't mean the AI builds more troops, it just means they are smarter and harder.
Religion Decay on, either way really.
Surround and Destroy Off coz ai doesn't take advantage of it, they're too dumb.
Advanced Economy on, free trade agreements seem to be the only difference and they're cool.
Barbarian Generals sure why not
Victory Conditions Mastery - who actually plays a civ game to the end? I can't remember ever doing so in a long time, usually I just either concede or am convinced there is no hope for the AI.
United Nations you can build it without winning the game - especially good for Mastery Victory condition.
Oh and one more important option I think is
No City Limits, I never would chose this option but I then tried it out and the AI does way better when the number of city limitation is lifted. You will also find the AI civs are more consistently even in score as opposed to just a couple of huge scores and lots of little ones. That reminds me of another option;
Vassals i don't like having them on but again, the AI does much better with them on, so let them have them. With vassals off however, the AI often backstabs others while they are in a war from another flank where the civilization is weak. When players have to commit armies to finish off civs and not just have them capitulate after a few turns, it adds more strategy, so its a bit of a toss up, I tend to switch between on and off.