What I always hated is the ones where someone customized and then couldn't stop! Made more & more changes and changed stuff just for the sake of changing stuff.
My own preference:
Don't change ride height by more than an inch
Do NOT use the 3 foot tall wheels with a single rubber band on 'em for a tire
I don't mind the "dipped in black paint" look on some cars, but it just doesn't do it for most cars.
I hate billet anything - always have
Some cars should NOT be customized - the original designer nailed it. Others need help. Some just can't be made to look good no matter what is done (or by who)
I don't see the purpose of airbags - if its too low to drive it, it just looks stupid, so why have a way to lower so much as to look stupid when its parked??