UCLA, Cass and LBS alumnus here, having bought/sold six businesses since my MBA, predictably saying that LBS is best. LBS is the leading UK business school in more or less every niche. Just compare the impact and the focus of the faculty and the alumni. The school has more than 20 years experience of running a venture fund, an incubator, and angel investor network and is home to one of Europe's biggest and best-funded entrepreneurship centres, the Deloitte Institute. The long format, and in particular the entreneurship summer school, will be very favorable for you to develop your business plan and network with partners and investors. Cass is good, but not on the same level.

Thank you, Duncan. Do you know if it is difficult to get work Visas for Americans who want to start their own business in UK after school? Just want to make sure these post grad goals are feasible.

You can Google the entrepreneurship visa. It seems pretty easy to me but I am not an expert.

You basically get a 12-month visa if you can demonstrate that you have a credible business idea. It's fairly straightforward and I believe business schools can actually sign off on the concept, versus having it approved by the UK government. Check with the schools on this, though.