My top five...
5: Dutch. The two new traits, but I like them. Good UU to defend stuff, no need to upgrade to or build Musketmen (more expensive to build Musketmen.)
4: Sumeria. Good traits, especially on a very arid map. Just try not to get into an early war until you're out of Despotism. Republic slingshot is helpful there.
3: Persia. Racing to Iron Working and rushing the AI with Immortals is what I like to do. Nice to get out of Despotism first, of course.
2: Babylon. Whether it is culture or space race, Babylon is excellent for peaceful building. Great civ.
1: Scandinavia. I never seem to grow very quickly with them, but that's fine by me. They're perfect for warmongering, particularly on Archipelago and even Continents maps. Berserks can even destroy Riflemen pretty easily and can get those one-tile islands if necessary.
Also like others like Greece and the Ottomans.