There was a pretty spirited debate over which was #1 - Religious or Industrious. I (and others) argued for Religious, while Velocyrix (and others )argued for Industrious. When the dust settled, Industrious had won. Not by a helluva lot, mind you
Militaristic CAN be the #1 trait if you use it correctly and are blessed with a bit of luck. I typically play militaristic civs, usually combining mil with either religious or industrious.
Scientific is ok, but generally accepted to be a 2nd-tier trait. It can be more useful for a builder to gain or extend a tech lead in a close race. The cheap science buildings are nice, of course.
Commercial, with the 1.29 boost, is a solid trait, but also 2nd-tier. On maps with lots of open land, combined with industrious (France), I could see it being pretty powerful over time.
Expansionist can either rock or suck. In my experience, it mostly sucks.
-Arrian