What's your favorite opening?
Combining having to play both sides of said Opening, it would be the French Defense, which I do play from both sides via 1.d4 e6 2.e4.
Individually by color?
White - Trompowsky Attack (I avoid it as Black via 1...e6)
Black - King's Gambit (I avoid it as White as I don't play 1.e4, and if I did, I wouldn't play the stupid move 2.f4??)
My favorite opening is The Danish Gambit