The most comfortable loc-on I've ever used is a Millenium loc-on, I could sit in it all day and be fine. The most shooter friendly loc-on I've tried is the Lone Wolf Alpha's. As far as climbers go, I use a API Bowhunter and will put a Summit seat on it this spring IF I don't break down and get a Lone Wolf HandClimber.
I will chose the satnd that best fits my needs for the hunt. If I'm going to sit more than 4 hours I want the Millenium, four or less the Lone Wolf, or my API Bowhunter.
I would strongly suggest that you try before you buy. I do not like a climber or any stand for that matter that has any kind of rail,bar or anything else that comes past the front edge of the seat, and I've never liked to "sit and climb" in any stand so a open front style stand is all I ever consider. Alot of people just aren't comfortable with this style stand though, different strokes for different folks. Try a few and find out what matters/works for you.