i'm using an old rc charger that's not that well specced by todays standards but it's been reliable for many moons. does need a seperate balancer though.
avoid those nuprol 3-led types, i've seen 4 or 5 on here (including one i owned) kill batteries when one of the charging circuits died (which is why i no longer run life batteries)
Turnigy Accucell 6 mainly due to cost and availability. It can charge anything you'll use and does so in a way that makes it pretty unlikely you'll blow something up. I actually went for it because I heard there were problems with counterfeit B6's and the Accucell is a Hobbyking thing that I could get directly from them.