Whilst I can't speak from experience having never gone to either uni, (went to Wolves), both Leeds & Sheffield are reasonably close by.
I would visit both. Go to the open days, speak to students who are studying there, speak to the lecturer's on the courses that you're thinking of studying, and put yourself in the shoes of a student - eg: fake going to a class, leaving the lecture hall, walking the corridors to the cafe, navigating the city centre, walking to the halls.
Imagine you actually study there, and if you feel like 'Yeah, I fit in, and enjoy this atmosphere', then you have a good idea whether that uni is for you.
If you don't enjoy it, or you get a weird vibe about the place, see how you felt at the other uni of choice.
If it helps, this is what I did when I chose Wolves. I did ICT, and for me, Wolves' IT building was within the main campus. I liked the fact I could leave the IT building, and be amongst all the students and the atmosphere of being at a university in a city centre. My other choices at the time were Staffordshire, Birmingham City Uni, Worcester and Coventry.
Nothing against the other uni's at all, but their IT buildings were nowhere near the city / main campus, and I knew that if I studied there, I would feel cut off from the rest of the uni 'lifestyle', I suppose.