I like exploring, but without a compelling plot to tie everything together I'll lose interest before too long. I also like more linear storytelling, particularly when the type of story being told benefits from it (Uncharted 2 wouldn't be the same game if it were non-linear for example).

I'll take either I suppose, but if a game leans too heavily towards exploration over story telling I'll generally get bored before I ever finish it, so I prefer that exploration never come at the expense of telling an interesting story.