For me it just comes down to evaluating what's gonna give the best concealment and best shot opportunity at 15 yards and under. I'll do whatever's necessary after that.
If I can get up a tree, that's usually my first choice. The treestand usually allows you to pull off a shot undetected, and typically without things getting in the way of your shooting form.
If there's no tree suitable, I'll make a natural ground blind.
Once in a while a spot will just naturally lend itself to a great ground ambush. If I feel both options will work just as well as the other, I'll take the ground. Less work