I have used both, and lets just use the lone wolf system as the example since they make both.

The lighter option is the climber, but neither are too heavy as to be burdensome.

The more versatile option is the hang-on, you can literally get in any tree.

The hang on is harder to set up, but again, not so much as to be a problem. Understand that you will need to do some taping and mods to the hang on and sticks to avoid metal on metal noise.

The climber is more comfortable.

If I had to choose between the two I'd pick the hang on, because I mostly bow hunt and it allows me to set up anywhere. It is a pain in the butt to have to set up either a climber or a hang on early in the morning in my opinion, so I might as well be able to get in the best tree. Also, if you know ahead of time where you are going to hunt. you can go in and limb those trees out and hang a "ez hook". I just love the concealment of a hang on.