I voted for the Americans as that is what I usually play as. I enjoy large or huge maps (pangea or continents). The early tech lead I usually get from huts helps tremendously, plus in about half the games I will get a free settler. Now, I haven't played above regent, so take this for what it's worth.
I personally think Industrious is the best trait in the game. I have tried other civs on these maps like the Babs or Japan, but I just can't stand it. Everytime I go to mine a hill or mountain and I see how long it's going to take my worker to accomplish this, I just want to take him out behind the woodshed and :slay:
When I want to play a smaller map I won't play as the Americans because the expansionist trait is worthless (or damn close to it) on these maps. Then I will usually play as the Egyptians or the Persians. (notice they are still Industrious)

I need to try the Chinese and the French on these maps as well. Haven't done that yet.
As far as the UU being worthless, yea, it is pretty much. It comes way to late but I never trigger GA's with UU's anyways unless I'm playing a smaller map as the Persians. On regent and below I can pretty much grab any wonder I want and 1 of them is always the Pyramids, especially on those large and huge maps. Then in the Middle ages when I snag Copernicus's Observatory my American civ goes into a GA at the perfect time to grab Newton's, Smith's and Leo's if I haven't already built it. I usually end up with an obscene treasury even after upgrading all my military. It's perfect. [dance]
One other thing I like about Expansionist is the fact that if I start in an area where there aren't any bonus food tiles I can build a granery to fuel my expansion, without having to research Pottery first. I already have it.