I am currently a first year at Sheffield law school so I can give you advice in relation to this.
I have never been to see Birmingham but all I will say, briefly, is that today I had a lecture from a partner in the banking department of Addleshaw Goddard explaining applications etc. People on TSR will no doubt say that Birmingham has a better rep, but the way I see it, if you go to a RG university, the firms will look at your application and then it is simply all about what you bring to the table.
In summary, there is not much real difference between the two. Go with preference.