While both programs are excellent, we're comparing apples to oranges here. I don't know that much about management programs, but the MSc Finance degree is perhaps the best program LSE has to offer.
An LBS or LSE degree promises a successful career in IB, so either is a great choice. But your choice also depends on what are your specific goals. A management-oriented future would be better served with the LBS degree, while a career with more market, financial, or economic analysis would fit better with LSE. It also depends on your personality. A person blessed with a quantitive mind will probably feel more comfortable in a financial environment.
For me, though, I would choose LSE. Finance is a powerful and versatile tool.
thanks! for LBS's program seems like a better brand, but my concern is that the topics are too broad, while the LSE's Ms in Finance is essential and specific info, but less name recognition..