G1: I ALWAYS wanted the boy ponies to come in Pegasus and Unicorn versions. Other than that I always wished for TAF versions of some of my favorite ponies, such as Moondancer and Heartthrob.
G2: Needed more unicorns and pegasi as well. Not to mention males.
G3: Also needed males. (Come on, Hasbro. Little girls like boys too, their fillies don't "usually" date each other.)
G4: More variation in the Mane 6. Oh, AND BOY PONIES IN FASHION SIZE. Seriously, Hasbro. Come on. Even my 7 year old daughter wants more boy ponies...sheesh...