I like the Dutch and the Maya, the Dutch being because of their generally great traits, and Swiss mercs are great for filling an early army, then walking around pillaging any unit in my path. Also, I guess the AI has this thing about odds, but if they don't have iron or invention, they'll avoid the swiss mercenaries like the plague.
The Maya have two of my favorite traits, and Javelin Thrower + industrious = overkill.
I have this dislike for Germany, mainly because of terrible circumstances in a former game where I started on an island supporting three cities, and a two-tile island near my native island. I had horses, but no iron and I built the GLH, attacked a coastal Incan city with a bunch of archers, and they couldn't beat just two spearmen.
That's because youre not supposed to attack like that with germany. At least in general. They are scientific and militaristic, militaristic yes, but they dont have anything for early game. Like industrious, agricultural, no early UU, no early alphabet. So they need some higher level units before they attack. And also they lack in mobility. I mean, you attack with medieval infantries/horseman or smthn a target thats far away, but because you're focusing on science, by the time medieval infantries/horseman or smthn get there you already might have knights, so you take 1 city, turn back, upgrade all your units and attack again... My belief is that they are same as ottoman, scientific industrious. Eventhou they have industrious, until siphai(8/3/3 cavalry replacer), they are pretty weak. And also no early golden age, so with those kindof civs imho its pretty hard to play like that. You take a risk, if you lose - youre put yourself in waay worse position compared to what other early civs could be.
P.S. Yeah i also like Maya, i think by the traits itself they should be most powerful civ in game!! But in reality it appears that they are lacking a lot of different stuff. For example theyr Javelin Thrower are good unit for capturing cities/defending, but far not the best. Tech tree by itself forces you to make warrior code early on, when instead you could make bronze working and iron working(Swordies vs Javelins) and you can upgrade them only to longbowman

. I think Three-man chariot, War chariot(egiptian chariot - my favorite

, Mounted warrior(probably best UU in entire game), Zulu imp, Dromon and few others are much better then Javelin Thrower. And also usually scientific civs are usually ahead in techs, seafaring in contacts=wealth(more gold, more everything). So when i play Mayans, i am almoust always in middle of everyone, only when my cities become crazy big, then i start to lead. But thats usually isnt happening so soon. And also i often get stuck on 12 population, due to lack of cathedrals/hospitals/colliseums in my cities(on Monarchy lack hospitals, on Republic lack cathedrals/collieums.)
So i dont know, they look really awesome at first, but i've played like 10 or more games with them and usually dont get as high score in the end as i would expect.... With egyptians i usually get such and overkill

))) I mean that just should NOT be happening. They conquer so friggin fast! Oh man

)))