Think of each university individually -
Are there any modules unique to this course, that you'd be interested in studying?
Are there any mandatory modules that you really don't think you'll enjoy?
What about placement / work experience opportunities?
What are your thoughts on the department's facilities?
What are your thoughts on the societies on offer there? - How active are they?
How expensive is the accommodation there? - Is that an issue for you?
Is there anything unique to that university that you're interested in?
Think about the area - what amusements (theatres,cinemas,museums) are there, that you're interested in? Are there any festivals/fairs that you'd like to go to? If you like gigs - how many times to big bands come to play there?
How expensive is the area to live?
Take the time to really research and provide detailed answered to all the questions for each university. You should then be able to more easily make a preference.
Have you looked at The Complete University's Guide to each university?
Sheffield ;
https://www.thecompleteuniversityguide.co.uk/sheffield/Manchester ;
https://www.thecompleteuniversityguide.co.uk/manchester/Birmingham ;
https://www.thecompleteuniversityguide.co.uk/birmingham/The Complete University Guide is useful because it covers;
History of the University, Location and Transport, Student Mix, Course Flexibility, Teaching Standards, Research Standards, Academic Strengths, Student Facilities, Disability Services, Student Union, Availability of Part Time Work, Careers Guidance, Prospective / New Builds, Notable Alumni, International Students, Fees and Finance, Reviews, and more.
Have you watched videos about each university? Watch the generic videos about the university, and ones about your course specifically. Also watch videos about other courses in your department, it might help you develop a fuller understanding of the department, facilities and staff. Also look to see if students have posted videos about their experiences at the university.
Don't hesitate to contact the universities directly with any questions. If you can, contact the departments directly. If not, then send an email with all your questions to the Admissions department who'll forward it on. Consider reaching out to the societies at the university. I found asking current students about the course, university, and surrounding area extremely helpful. Consider looking for Facebook groups related to each of the university there and speaking to current / prospective students as well. Also, congratulations on your offers!
Take your time to research things. Just try simple google searches, and you'll be surprised by the amount you can find out about a city. I've travelled through to Manchester a few times (from Scotland) and I've found it a really nice place. All the people there that I've met have been really friendly. It's a really good place for gigs. I know there's a few museums there, but I haven't been personally. See if there's an tour guide videos to each area and give them a watch!