I used to live in Newcastle-under-Lyme, Staffordshire, so I wasn't far from Rugeley, just up the A51. Rugeley has two rail stations, so that's a good start for transport links, especially for the size of the town; also a regular bus service to Stafford. You have two power stations dominating Rugeley, but to compensate you have plenty of nice countryside, notably Cannock Chase. Rugeley is much different and smaller compared to the other three places you mention. Not as good for shopping, at least when I lived in Staffordshire (4+ years ago). However, Stafford is nearby for a larger selection of retail outlets.
I can't comment on Dunstable, never been there. The town of Doncaster is nothing to write home about, although I have warm memories of visits there. Once you get out of urban Coventry there is some beautiful surrounding countryside with attractive small villages.