i'm bias, but i love bama's. simple, classic, timeless, and recognizable.
really like nebraska's as well.
i like osu's, but not the stickers. i appreciate the tradition, and it's really cool so i wouldn't change it. but it does, imo, ruin the helmet's look a bit.
mich is also a good one outside of the "simple" realm. not that it's busy, but it's unique.
nd is another good one.
au has nice one as well. i must begrudgingly admit they have a good overall uniform, even if the colors suck.
for non-bog boys, i like csu rams. my hs was rams and we had similar helmets, thought different colors. but the curling horns is a great look on a helmet, imo.
lots of teams have done this recently, but i really like the matte finishes as well.