Summit Climbers! They're rock solid and can take a lot of abuse. After 4 seasons with my bBushmaster and 3 with my Viper I have to say I've never once felt unsafe while in them or going up or down. Confidence in your equipment is a very nice thing to have! I'll give you my opinion of API while I'm at it as it's the only other treestand I have used....not worth even trying...the grippers on the platform are too small and seem to 'spin' if you shift your weight from center to the side....I was scared....I climbed down....I sold it the next day and bought a Summit...no slips since. That, of course, is just my opinion, but it was a great decision IMO.

As far as hang-ons go, I'd go with something that has a strap rather than a chain and add climbing sticks to it. I own a Big Game Boss and it's very comfortable and solid....a little heavy, but if you're keeping it stationary for a long duration it doesn't really matter that much about the weight.