PKR is good fun, plus because of the software, most players are very fishy I find. No satellite strategy, saw someone shove 15 big blinds with AJ offsuit under the gun on the satellite bubble, to be called by KK and get knocked out. Plus, you can type in expletives, which is always nice (you have to change your settings to be able to view them instead of ****). Traffic could be better though.
I find iPoker really soft, albeit the software is a bit dreary. Paddy Power, in particular has some awesome MTT promotions for micro players especially, for example, play two specific $1.10 MTTs (with a $100 added prizepool) in a week and get entered into a weekly $1k GTD freeroll. Play 2 specific freerolls
on monday and tuesday and get into the final on friday. iPoker sites
also have good quality traffic at peak times on all hold 'em games and surprisingly good traffic at micro PLO.
However, there is no questioning the software, traffic, promotions and variations of poker available on Pokerstars. For new players, the PokerSchoolOnline site is a great way to start learning and then by completing the quizzes, getting free tournament tokens (only if you have not deposited yet). There are a lot of regulars, however, its always quite exciting to have someone like Lex Veldhuis or Liv Boeree on your table .
It really depends on what you like. In my opinion, once you go Pokerstars, there's no going back (unless you ban yourself for 6 months).