1. Brock Lesnar
Pros: This match would be brutal, angry, and very, very entertaining. The pair have unfinished business since Austin's refusal to put Lesnar over at the beginning of the Minnesotan's rise in the early 2000s. While it would break kayfabe to reference this directly, the WWE have become surprisingly adept at spinning real backstage rivalries into storyline heat (evident from the Punk/Cena feud's repeated references to the latter seeing the former as 'the guy who couldn't hang'). Cons: It's hard to think of too many downsides to this potential encounter, but one hinderance could be the age of both men. Neither are young by any stretch of the imagination, perhaps depriving this clash the length it deserves - although its level of intensity would never be in doubt.