I think probably shrimp, in almost all forms: steamed, fried, boiled, in stir-fries, au gratin, in curries, pasta sauces etc. etc. etc. Don't really like them raw, though ceviche's good.
Scallops (esp. Digbys in NS!): deep-fried, lightly coated w/ seasoned flour & pan-fried w/ garlic and parsley (or with white wine, mushrooms, scallions or, or). Prefer them cooked too, although ceviche works!
Crab cakes - gotta get with the Maryland thing!
Lobster in almost all forms, esp. Asian styles.
Clams: Fried (whole please!), w/ pasta.
Oysters: raw, fried, Bienville, Rockefeller etc.
Salmon (pref. non-Farmed): grilled or broiled.
Tuna: lightly grilled or broiled, sushi.
Also never met a seafood soup I didn't like - Bouillabaisse, Bourride, Tom Yam Kung, Gumbo, Cioppino, Soupe au Poisson etc etc....