I find it's a bit of a moving target and depends a lot on my mood at the time; generally speaking, exploration, the wonder of finding new places and random interesting stuff. It's the bits of the story that aren't so much told as experienced, I suppose.
As much as I'm tempted to say "anything but the combat", that's actually a lie. I can't deny that occasionally (perhaps even often) I find it genuinely fun and enjoy the sense of achievement provided getting there hasn't already made me gnaw my own legs off in frustration. Just as long as that's not all there is.
