I have used Summit, API, Lone Wolf, the old Baker's and probably a few more that I can't think of right now. IMO the Summit Viper, Goliath and Titan offer the best combination of comfort, safety, ease of climbing, and relatively easy to pack in and out of the woods. My vote goes for Summit but I will offer two other suggestions I have not seen in earlier posts.
If you can find a TreeWalker check them out......very well made and made in the USA I might add.
Since you mentioned all day sitting, you need to check out a Tree Lounge. I heard that Tree Lounge had once again closed but I'm not sure on this. For all day hunts, these stands are great. I found one at a yard sale for $100 bucks and hesitated on buying it. Stand looked as if it had only seen a couple hunts. Went back later only to find they sold it for $75.
Another to check out for long, all day hunts is the Gunslinger. These allow you to face the tree for a little added cover and are really comfortable. A friend of mine has one of these and loves it. They are a little heavy, bulky, and take a little more time to set up.
www.jrhsport.com/gunslinger.htm