Stats-wise, on The Complete University Guide, KCL is best of those overall for this subject. Entry standards are also highest at KCL, out of all of those universities, for this subject. That said, my heart is never with London as a place to have 'the undergraduate experience'. I like a university to unequivocally be a major point of its city, not just one of many parts. That's just a bias of mine though. It's not categorically correct and there's no business like the business of London I guess but it's just a bit too obvious to me and I think successful business comes from struggling against an archetype, not just aligning yourself on your CV with an epicentre of business.