I enjoy books which had meaning in the imagery and the metaphors they use, the fact that the author took time to pick their words carefully makes its seem more worthwhile. This is more common in older books I've found and often have one over riding theme/idea/view. The curious case of Dr Jekyll and Mr Hyde does this particularly well and is a great read.
That being said if its a good story that totally sucks me in I don't care about genre, it's all about immersion for me. Harry potter, Artemis Fowl and LOTR books I find pretty good for this.
The book I'm reading at the moment is "The Audacity Of Hope" by Barack Obama, I figured this was something is SHOULD read but it is actually pretty good and I find myself agreeing with a )lot of his ideas (haven't finished it yet though"