Any info you might have on any of these bindings would be a great help. I'm going to try and look up some info on them now myself, but I'd really like to know what other people who've used them think about them. Thanks!
a lot of it depends on what kind of riding you want to do and where you are skill level-wise. i rode Ride EX for a couple seasons (just switched to something else this season) as an intermediate rider, and i feel like they really helped me progress quite a bit. i also think they're a pretty good value as far as bindings go. others may disagree with that take. i don't really know anything about the other ones you mentioned.
I've not ridden them, but several of the guys at my local boardshop wer pretty hot on the K-2 indy's. They all felt that dollar for dollar they were the best binding at the price point. Again, only a word of mouth recommendation, but one I heard more than once. I never found them at as deep a discount as other bindings, though, so not what I picked up this year.
If you are more of a freestyle person, you may also want to look into Flux bindings. I had a pair of Burton Custom Detox and Ride Delta Movements and had problems with both of them. Never used the K2's though.