oh uh ... i forgot to say, there is no "best civ" ... most are very good. your play style and type of victory are going to affect some things. if you want to build a lot of cities with a good infrastructure you should try out an industrious civ. if you want to beat the pants off your neighbors make sure to be militaristic. if you want to be a republic raking in the cash go commercial. if you need help defending your cities in the ancient age be greece so you get hoplites for spearmen cost. if you need medieval attacking power choose china or japan. etc etc.
certain civs to be wary of ...
spain - great traits. but their unique unit is almost useless except to kill workers and cut resources. the only good thing about it is that it comes at the cusp of the industrial age, giving you a sweet golden age if you haven't had it. i only play spain for role playing purposes (but i do play them a lot).
korea - erm ... good traits but their crazy cannon unit won't trigger a golden age. it does allow you to use the infantry/artillery city seige strategy with musketmen, archers, and rockets, but the downside is that they can't be upgraded to missile artillery, should you ever need those.
celts - celtic swordsmen are hideously overpriced.
carthage - nummies are powerful defenders but are expensive.
france - you have to be pink unless you edit the scenario with the included, installed editor.
mongolia - no dental plan
vikings - beserkers are a waste of money if you don't take advantage of their marine abilities
england - super lame boat unit that is useless once steamboats are invented
and so on and so forth. i recommend continuing to play around with the civs. you'll find a few traits that you favor and will become good at using those, and you'll know which to avoid. (for example, i never play an expansionist civ. i kill the closest 3 civs to me anyway so techs aren't my problem

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