Both are great, but I think I like Ages a bit more. The shift between centuries offers more changes in the landscape than between seasons. And there are Zoras, and the Gorons feel a bit more important too. On the other hand, Seasons has Subrosians and Biggoron, and well... It's close, I like the games almost equally, but Ages is a teeny bit higher.
I suck at 2D games but I like OoX a lot anyway

Truly great games. For some reason I love all the color based puzzles, and overall the dungeons and puzzles are pretty great. And the people are fun.