Personally, I'd rather try to like where I study more than the ranking - After all, if you're not enjoying things, you won't be motivated to do much with your degree years. Both universities are well up there anyway, and a good degree at most universities in engineering will serve you well.
How do you find this out? Well, going to open days is really useful. A university will likely click and you'll just want to stay there. Sometimes the facilities just inspire you. I did enjoy looking around the aerospace departments at Manchester - I haven't been to Sheffield, but it's really up to you.