Aston Business School definitely had a better reputaion than QMUL, not forgetting the living costs. Its much cheaper in Aston. aston is also much smaller giving a more community feel. Everyone has also been very friendly and helpful at aston whenever I went to visit. so yeah, aston anytime =)
I'm from Australia and I know little about universities in the UK. I've heard good things of Aston, I've not heard of QMUL. I guess if you're going to base it upon international reputation (which being an international student I imagine that you will want to work in other countries as well) you should go for Aston.