Bear/cougar/coyote/whistle pig. Anything you shoot and don't eat. Just can't do it.
With Bear meat I can't get trichinosis out of my mind, not rational, because I understand if it's cooked properly (> 160 degrees) I won't get it.
Every year I think about waterfowl hunting but never enough interest to try it. Sitting for prolonged periods of time in the dead of winter probably has a lot to do with it.
Tree stand hunting. Again, sitting in the same spot, not my thing.
High fence or private land hunting is a no go. The element of fair chase dissipates and I lose the satisfaction/pride of harvesting an animal on public land. Speaking from experience, I did a high fence once for pig, it was not satisfying.