Most aggressive opening for white after 1. e4 e5?


When my students ask for aggressive 1.e4 e5 openings, I give them my "13 Dangerous Openings - Choose Your Weapon!" handout. And the winners are (in no particular order):
1.Boden Gambit 2.Urusov Gambit 3.Center Game (castle long, storm the Black kingside) 4.Halloween Gambit 5.Evans Gambit 6.Max Lange Attack (4.d4 vs the Guioco Piano) 7.Moller Attack in the Guioco Piano 8.Four Knights Opening (delayed castling, storm the Black Kingside versions) 9.Ponziani Opening 10.Vienna Gambit 11.Scotch Gambit 12.King's Gambit Delayed (Bishop's Opening with 5.f4).
Out of ones you mentioned - King's Gambit is most aggressive. I play it occasionally myself, and it usually leads to fun games.
Out of ones you didn't mention - perhaps Vienna? There are a number of ways it can be played, but the including an early f4 from White can be pretty double-edged.