LSE vs UCL mathematics

I have conditional offers from both LSE and UCL, (A*AA for LSE, A*A*A UCL, I do Maths, Further Maths, Physics) to study Maths with Economics and Mathematics respectively. I am confident that I can achieve both offers, so the offer difficulty is not something that I will base my decision on.
However, I am very skeptical and want some advice.

I prefer the UCL course, as I would like my degree to be fully based in Mathematics to be more flexible (i want to do some physics) and be able to explore Maths in more depth. I don't know what I want to do after my degree and a maths degree keeps more options open. If I excel in my degree perhaps I could go for a PhD later as I love math. Also, I would like to have the option of working in a scientific environment (something with mathematical physics) in the future as I really like physics, which I won't be able with the LSE programme.

However, LSE is LSE and its reputation cannot be neglected. I said I prefer the UCL course but it's not that I hate economics. There are some financial topics that I find very interesting, and although not sure, my career will most probably be in the financial sector (investment banking, actuary, etc.) and LSE's reputation in the sector is huge, maybe even ahead of Oxbridge.

I'm really in a huge dilemma, it's basically what I seem to like most versus what would be a more sensible choice (Career-based).

thanks