Good Ol' 02s
I'll start by saying that I really do dig these bindings- they've taken me many cool places, and performed in some sticky situations. I have two pairs of these that I've been on for the past 4-5 years, in both Big Mountain and Park skiing. I've had to pick up the small cartridges for both (if you do this, make sure they give you the smaller housing as well, or else they'll still be loose if you have a small boot). But yes- they tend to loosen themselves when you ski, so you are constantly having to tighten them up. They recently came out with newer cartridges that supposedly helped fix this issue- I haven't tried any of the recent models, so I can't say for sure. They also recommend throwing on a piece of tape to decrease the chance of them loosening up when skiing.
Overall, even though it's a bit of a pain having to make sure that your bindings are tightened up at the beginning of each day, I still love the 02s. They're great for charging, throwing down in the park, and just having a good time!