I am assuming that you are going to play 6max NL, rather than full ring?
If so, I would go with the Prima network. Lots of decent deposit bonuses (the current top two on
www.easypokerbonuses.com for example), and plenty of 6max tables at low stakes.
The software does kinda suck, but it is super-fast, so you do get more hands per hour than at any other site, IMO.
Lots of shockingly inept players!