With fantasy, you enter a completely different realm. It provides the ultimate form of escapism. I need my stories to be more rooted in reality, though. I do like some urban fantasy.
Escapism is it I imagine; having something greater than reality...or different, so it makes more interesting than the world we live in. Whilst I have quite a varied taste, but that is what I seek when reading fantasy. Perhaps call it 'idealism'...though I suppose not all settings are 'ideal', especially if you were to look at some my fantasy attempts.
The gap between those who chose Fantasy versus General Fiction is really small. That surprises me. Most of my friends read fantasy, especially the guys.
I am outside the age range, but I wouldn't have picked a genre anyway. I read different things for different reasons- all of which I find satisfying. My brother is in the range, and he would pick Fantasy.