As a general rule, I like long hair on guys, but...
That particular "mop top" style of long hair doesn't do you justice. Somehow with the long hair you look sort of plain...it overwhelms you and hides your best features.
With the short hair you look totally hot. It shows off your face and your features look more balanced.
If you want to, you can probably pull off thicker, longer hair, but pick a style that keeps the hair off your face. You don't look as good with bangs; they hide your eyes too much.