1. Party Poker - no % seeing flop (major -ve point). Fairly fast play, no micro stakes, no very small-stakes SnGs. Nice offers to get you back (have given me over $50 without me redepositing). Not my #1, but some plus points.
2. Poker Stars - not enough Omaha H/L SnGs going (too many SnG options to some extent, so they don't fill up as easily as they would if less were available), otherwise a good selection of games and stakes.
3. Absolute Poker - crap freerolls, pretty decent otherwise
4. Ultimate Bet
5. Full Tilt - has some unusual games - e.g. Razz, HORSE
6. Paradise Poker - soft competition - my most profitable site to date
7. Doyles Room
8. Americas Cardroom
9. Bodog Poker
10. Pacific Poker. Some very soft Omaha H/L cash games which are worth playing. Hopeless for non-Holdem SnGs or MTTs.
11. Empire Poker
12. Golden Palace Poker
13. Bet365 - standard Prima site
14. Bet Fair Poker
16. Victor Chandler Poker
17. Poker.com - regular freerolls fill up quickly. Private tables. Haven't played for cash on there yet
18. Hollywood Poker
19. Nine.com - you've got to be joking, right? Last time I checked them out they only had Holdem going, and the game selection was hardly encouraging... having signed up as an affiliate I decided there was no way I was going to actually waste time trying to promote them
20. World Poker Exchange.
The Prima sites (32red, PokerTime, Bet365, etc) should be grouped together, as should the Cryptologic sites (InterPoker, William Hill
?, etc), and other gaming network sites which share players, as the level of play and quality of software will be fairly comparable.
iPoker (Titan,Noble,CDPoker) is missing, and has good, soft short-handed SnGs which are worth playing, certainly more worth joining than the likes of Nine.com.
Pokerroom.com is missing from the list, although it may be the same network as Hollywood or something, but it has nice private tables and decent software.
A general rating isn't of that much value, because some people will want to play for decent bonuses, some look for good software, some for fast games, some look for soft competition, some for a good range of games (e.g. lots of non-Holdem games). You can't really do a single list that does justice to all those different requirements.
My top 5 would be:
Paradise, Stars, Pacific, Prima, Party.