Obviously it has to be someone who's a big fan of the show (that rules out George Lamb). They also must be in possession of a personality (exit stage left Emma Willis) and preferably have a sense of humour (laters Keith Lemon).
I know exactly who should present it, but I don't know who he is. They went through a stage of having guest presenters for BBBM and one of them was excellent. He had a lot of charisma and was actually quite funny. I think he was young. Anyway, that bloke who I have absolutely no clue who he is, it's him, he's the one, he should definitely do it!