I like both. But I think it's hard to find good Shonen, so I usally read most Shoujo..... But of course I would have read Shonen if I could find a good one.
Death Note, One Piece, Detective Conan, Ranma 1/2, Inuyasha, Dragoonball and Naruto is good Shonen!
Kamikaze Kaitou Jeanne(and all of Arina's manga), Milk crown(H, Lovers), Koigoro Fantasia, Knighty Knight Fruit Basket and Penguin Brothers is good Shoujo!