I would always recommend Queen Mary. It's brilliant for History courses and Politics courses. I'd say it's definitely better in terms of the staff and general uni life and apparently the courses are very enjoyable. I don't attend either myself but from what I've heard you should definitely go for Queen Mary. x
Which uni is best for Politics..and which uni is better or more respected in general.. And why :)
Which uni is best completely depends on what you want from a university. They'll both have different strengths - have you compared the course content and other opportunities like study abroad at both universities? You'll find that even though they're both called 'politics' that they're likely to focus on totally different aspects of the subject.
You should also look into things like chances to take additional subjects, societies and also things like accommodation or financial bursaries.
What I think is better for me might not be the best one for you.