My dad is a partner in a law firm so from anecdotal advise he has given to me as someone hiring graduates, if you attended a strong uni with good rep they are kind of all the looked at similarly. Manchester Leeds and York are all very very good law schools so shouldn't be the ultimate deciding factor in most cases. Main piece of advice would be to look at all the optional modules on each uni's course and see which are the most appealing to you. Obviously other factors to take into consideration when choosing where to apply but between them 3 in 99% of cases it will make minimal difference for employability. I can't speak in terms of Magic / Silver circle firms but all 3 of them are excellent law schools so wouldn't stress over the employability side too much when choosing between the three.