Quote Originally Posted by Excalibur
Which limit is most profitable?
Can I make more by playing lower limits on another website?
And if that's the case... Which websites feature these limits?
You should play at stakes (try not to say "limits" -- it conveys the wrong thing) that are appropriate for your bankroll, provided you can beat the game at that level.

If you only have $100 to your name, .25/.50 is not advisable. If you have $1,000 to your name but suck at poker, .25/.50 is still not advisable.

You want 300 big bets usually. This is an LHE rule, but more or less applies to NL. $150 is the minimum for a .25/.50 game, even if you can beat it.

I don't know that any stakes are inherently more profitable than other stakes. To put it another way, $1,000/$2,000 is probably the most profitable, because if you're playing at that level then you're Amazing as Hell at poker. The stakes you play are determined by your BR and your skill level.