Honestly, I'm leaning that way too. Stipe is probably the greatest heavyweight the UFC has ever had, has excellent striking and wrestling, and has only lost once without being knocked out (and you know Jones isn't going to KO him). Of course, he'll also be 42 this year and hasn't fought in three years.
That said, we know Stipe can go five rounds. The only time Aspinall has had a fight longer than 7 minutes, he's lost. What happens when he can't KO Jones? What happens when he can't take Jones down? What happens when the fight goes past the second round and he's got no gas left in the tank?
I just don't see Jones losing by finish to anyone, and if the fight goes 25 minutes, I like Stipe's chances a whole lot better than I like Aspinall's.