Imperial or Warwick

Neither will give you an advantage over the other. Recruiters don't really "target" these schools in the sense that they want to prioritise one over the other. There are just too many applicants now and banks want diversity in their classes. When you get to the level of Warwick, Imperial, LSE etc (and increasingly schools like Durham and Nottingham) you just tick a box on the academic side of the application which suggests you are intelligent. They're not going to actually be impressed by what you do or where, its just the bare minimum so you don't get extra credit. Obviously, outside of like T10/T15 schools this drops off, but only like 5-10% of applicants from targets will get good offers.

Neither is objectively better than the other, you'll see some people comment that WW is only targeted for maths and econ but this is a retarded take because no recruiter is going to be pedantic enough to figure out what subjects are more prestigious at some random university. WW and ICL have a lot of representation in traditional finance, for quant finance imperial is much more respected, however. Although I'm not too sure how your degree would be viewed as they tend to prefer maths/CS/Physics etc.

You should decide based on these factors:

1. Which degree do you prefer? STEM degrees are a pain and are hard, you gotta really like your degree to get a 2:1+.
2. What type of experience do you want? WW is campus-based and Imperial is a city uni. Imperial is mostly international students (as is most of London) and male-dominated, Warwick is not.
3. London is expensive, but also has more to offer.

EDIT: WW definitely has more finance hardos there so the societies and social circles may be more helpful.