Ground blinds are fine...its just that you are right down with the deer at their level and they generally look for threats on the ground also.
Tree stands get you up a bit so YOU can see farther and also get out of their immediate vision.....they listen 360 degrees and smell whatever the wind carries so that's important to think about too.

I've taken plenty of deer from both.

edit- I'll be hanging stands this weekend AND setting up a ground blind at one spot in case my daughter comes out....she doesn't care for tree stands either, lol. It's no big deal.