Borderlands 2 is pretty fun, but I'm not too big of a fan of Planetside 2. I'd probably like it more if I was good at it. I think that's how it works. I think my favorite "2" is Team Fortress 2.
Oh, I've never played 1, so this is coming from a newbie point of view. You know it's good, though, when someone who doesn't necessarily enjoy FPS's enjoys an FPS.
Yeah I'll pick up Payday 2 next steam sale. I've got Payday 1, but Payday 2 offers ways of completing missions other than the 1) get assault rifle, 2) kill every police/SWAT officer in the city mechanic that was required in every mission in 1, lol.