I play the $1 45 player turbo sngs at pokerstars - also $3 and $7 I think..
looked at the 90 player, but woould take too long for me.
non-turbo sngs have double the rake I think and take too long so not for me!
in terms of rake the $2 bounty sngs on merge are good ($0.20 total rake in the 6 player sng, or about 2%, as they add $1 to prizepool)
ipoker have the jackpot sngs if you think you're really good (win 5 in a row for jackpot of about 500 times buyin or so?)
full tilt have their academy sng challenges, so can get points (still waiting to find out what they're worth) whilst playing sngs....(worth it if on rakeback as well!)
lots of sites (eg pokerstars 'battle of the planets', merge normal leaderboard and 'streaker' leaderboard) have leaderboards for 1 table sngs
(eu only) have awful rake (20%), but equally awful players in the 30 player $3 sngs...
worlds worst players play at bodog and 888
depends on what exactly you are after, but all of above worth looking into...