Hubpages is definitely miles above the other sites on which I write because it has a really flexible platform and allows me to use my marketing skills to their best advantage (other than on my own sites).
Second would have to be Helium. It is second-best in earnings, and posting is very fast and painless. While keeping a rating star in order to get paid can be a pain, it really doesn't take much time and it does cut inactive members out of the pool and leaves more for those of us who are still trying hard to contribute to the community.
The other sites I write on are Epinions.com/Shopping.com and Associated Content. AC is alright for earnings, but not as good as Helium (and I'm at clout 8 so my pay is higher than starters). Epinions/Shopping really suck for pay until you get a "hat" (i.e. Advisor, Top Reviewer) but the community there really helped my review writing by leaps and bounds, so I've stayed there too.