vote for LBS, (but its FT ranking is inflated by British media. It's a great school, but cannot be comparable to H/W/S, more similar to Columbia, Chicago)
London is one of the financial center of the world, big finance company recuit in campus every year. In 2007, the first world-wide alumni reunion was sponsored by a IB (do not remember the name, I know nothing about finance but I studied in LBS for few weeks before).