At the time the prices were the same so my choice was purely personal preference(I think the Atlas is a little more now). I like that I can park the wedge into the wind if I'm really worried about it, but the biggest reason for me is that the bed swings up with the angle of the roof to open up the entire bed space for standing. Yes, the Atlas allows full bed length standing when the bed is out of the way. I believe, however, that it involves stacking sections of the bed to accomplish that instead of just raising the bed? I could be wrong.
I will say, the end of the bed near the front can get a little cramped. AT was willing, however, to move the hinge-point of the bed back 6 inches for a little more toe room. That does take 6 inches away from standing room when the bed is down, but it's still enough for me to climb up/down comfortably.