I would second the P280, I would also suggest the Fractal Design Define R3 ...and the Corsair 550D, there is also the Corsair 500R which is more of a 'gaming' case with regards to the airflow than the quiet ones I have mentioned ...also for another 20 quid there is the BitFenix Shinobi XL. You could also consider a Lian Li PC-7FN (there is the FNW with window also) and PC-60FN.
Although the Lian Li mid towers seem to have fallen out of favour with the community at large, I am still a big fan of their design and build ...there are a couple of points you should note with them though, firstly they are more prone to resonance than most cases due to their light weight aluminium structure and the panels are fairly thin tbh (not like classic ATCS designs from the late '90s early '00s) ...and for some reason I do not understand at all, Lian Li mounts their hard drives the opposite way around to the industry convention, i.e. they have the cables facing outwards into the case rather than backwards towards the right side panel as most cases do, I am not sure how easy it is to mount them 'backwards' though, it might be easy and thus not an issue.