Leather
Leather, hands down. I've had both over the years and only one bad experience when it comes to leather. And that is with our current 2005 Ford Expedition. It just came with crappy leather.
Pros to leather: Easy to clean, you wipe it down and it's clean. Easy to care for. I condition my leather about 3 or 4 times a year and it stays looking new. My 2001 Superduty's leather looked new when I sold it last year. Plus I think it looks classy.
Cloth, well, I hate that no matter how much you clean it, you can slap you hand down on the seat and still see dust fly up. It seems I could never truly get it clean. And I can't say that from "my" personal experience it's any easier to clean or any more stain resistant. I've gotten grease on my leather seats and cleaned it off.
So, that's my 2 cents.