I have done it both ways and actually find it more comfortable to shoot sitting. However, my range of coverage is far more limited in the sitting position.

I prefer to stand: first, I need to watch 360 degrees which I find to be much easier standing. Second, I can position for a shot over about 270 degrees including some while facing the tree as opposed to at most 120 degrees while sitting. Also, it is much easier to position for a very close shot while standing.

Like others, I try to avoid the need to stand when the deer appear by spending the prime time portion of the hunt already standing.

Most of my hunting lately has been from ladder stands. I buy the cheap ($50) stands at Dick's because there is a very good chance of a more valuable stand getting stolen, but I would much prefer a more expensive model with a flip-up seat. My Lone Wolf hand climber is supposed to be suitable for flipping up the seat, but then I would have to give up the extra security of strapping the seat to the platform. A flip up seat arrangement would be a huge improvement in comfort: I could stand and lean against the tree.