I don't know why, but medieval fantasy always had the most draw for me - real-life is too, well, boring, and sci-fi was too imaginary (everyone had their own slant to it).
Medieval fantasy had a real-life basis (and thus continuity of a sort), while having cool aspects like magic, dragons, and such
(Dragons are cooler than aliens...)
Incidentally, I bought the Spelljammer boxed set when I was young, but I never could make sense of it...