OH NO! A LONG REPLY!
All of the classes where fine, in terms of 'easiness' I would say chemistry, since it is basically pushing a few buttons. The hardest one is Shop, only because sometimes the game thinks you pushed left instead of rotating left.
The funnest class? I would have to say photography, followed by art and english in seconds, and gym in last. Photography is fun because you run around everywhere taking pictures, a little bit challenging too. Art is fun because it reminds me of that old game that I used to play. English is sort of a puzzle-type game, which appeals to me. Gym is fun, but not as fun as the others, gets better when you face the townie after you beat gym 5.