Neither.
Prestige is rendered pretty much into nothing after Oxbridge (could extend that to Imperial for being a well renowned STEM uni).
In terms of the top universities outside of the ones mentioned, there is very little if anything between the rep a university.
Personally I'd say Manchester because it is a large and well know city which will help with international job applications.
People will hate this view I have on this matter and neg me without calling me on it because they have no response. So I will take all negs as 'you are right but I hate this view therefore I shall show my hatred towards it and neg it but obviously not argue since you are right'
In other words unless you are applying to Oxford, Cambridge or Imperial (if doing a STEM subject) you would be a bit of a fool if you chose a course based on the prestige of a uni.
Of course bragging rights is a serious factor you must consider when applying. There is nothing I like better than telling people that I go to a better university than they do and therefore I am a superior person. I love when they try and argue, all I need to do is show how old the stone work at my uni is and then slap down the rankings table from a very tory newspaper and watch them cry as they discover us torries don't think their university is in the top 5. Then I urinate on them as they curl into a ball and weep. So yeah, make sure you factor in prestige when applying.