The Hogs helmet is certainly one of the most unique in all the land!
Apart from it, I also like the Arizona State helmets, with the Sun Devil Logo.
The Southern Cal logo is also a classic. The Michigan helmets are also classic (maybe not your definition of 'pretty', but certainly distinctive and unmistakable when you see them).
Georgia's are certainly distinctive, too, as are South Carolina's. Between the two, Georgia's are far more vivid and colorful, but I think I like the Gamecocks a little better.
The Ole Miss helmets look like they might have been done by some kid in elementary school, with a cheap marker. That cursive 'Ole Miss' doesn't do much, at all.
Florida did a much better job of that sort of design with their orange 'Gators' helmets.
Love the Gold color on Notre Dame's helmets!
Too bad more schools don't have Gold as one of their school colors.
The combo of Gold with either Black or Green almost always looks really sharp!