My feeling before was Leanord Bundu. Feather fisted, unbeaten (27-0 v 26-0-1 makes a lovely figth poster), European champion and ranked in the top 10 WBA. Perfect fight to sale to the casuals, gives brook a legitamte belt and more experience in fighting a southpaw
Eddie Hearn was quoted as saying "the British public aren't mugs and won't turn up to see a Kell work out" I hope he sticks to his word and does bring over an elite level fighter but IMO I just can't see past it being a relatively unknown fighter as a prep to a world title shot in autumn/winter.
i reckon while hearn popped over to sort the froch/bute fight he's had a chat with bute's stablemate ionut dan ion and that'll be brooks next opponent, not a bad opponent, took aydin the distance twice and has a good rankin with the wbc. http://boxrec.com/list_bouts.php?human_id=249042&cat=boxer