Rock climbing harness. Cheaper, safer, easier to put on, doesn't need a tether replaced after a fall, and doesn't rip you a new one from the jolt of a fall.
I worked at Seat-O-the Pants for a few years and tested all of them and wore them very briefly. They are fine until you fall out of the tree. You can smack your face into the tree, and it feels like getting kicked in the nads. Not to mention your legs lose circulation and fall off if you get stuck there too long. Seriously, full body harnesses are dangerous and I can't understand why they are still popular.
Think about it, a climber may fall several times in an afternoon and it's no big deal. You are just left sitting there, actually fairly comfortably. And no worries of your face smacking into the tree without your knees/legs actually taking some of the blow.
YMMV, and use what you feel most comfortable with. The one you don't wear for whatever reason is the only "bad" choice.