Im in sort-of similar position to you, these are my thoughts.
Personally, I would choose between Durham and UCL. Due to being very reputable and a nice contrast. One on hand, you have a collegiate university that’s not in the city. On the other hand you have a London based uni, which for me, would be more expensive and the social life wouldn’t be the same as Durham etc.
This all being said, not everything is about a uni’s reputation - whilst Exeter may not be as reputable in respect to your other choices, it is still a great university to graduate from.
If you feel that Exeter is the one, and you if feel that you’d have a better 3 years, don’t ignore those thoughts just because of a reputation!
Also, I’d take into account the respective entry requirements for when it comes to firm/insurance.