I've been to Air Force, UCLA, Wyoming, UNLV, Cincinnati, Notre Dame, and Middle Tennessee.
UNLV was the worst. That said, it wasn't that awful. A few drunken "eff BYU"s were heard as we walked through the parking lot, but that was it. Wyoming was really down the year I went, so I imagine nobody had the energy to try and be angry.
Cincinnati was the best. Their fans were all super nice and friendly. Notre Dame was pretty good too.