Well, Maverick vs Death and Taxes is one of my favorites. Between their flyers, your fatties, their revokers, your pridemages, their flickerwhisps, and your sweepers--the matchup is super even and super interactive.
But I had also assumed that he was asking for a deck that is super different from his current list. Usually the "____ vs ____" deck boxes have a theme about them about two opposite philosophies or colors fighting each other.