I would actually take Warwick over Durham.
Durham has been around for so long, and yet its reputation has remained largely unchanged. I know rankings aren't everything, but they're consistently at the same level every single year.
On the other hand, Warwick is a much newer university, and considering the fact that they haven't been around for very long, the progress that they've made is incredible. Every year they get a little better.
Also, Warwick does a lot more to try to boost their international status. They have the potential to become quite well-known outside the UK (largely because of their corporate ties), which in the long run is better for job opportunities and everything. Whereas to be perfectly honest, there are many people outside of the UK (I know I'm making a generalization) that have never heard of Durham before.