Hi, They all seem like very good choices. I only know of the top 4 places, but thought you might want to know that the local reputations for the best schools would be in this rank:
Cirencester / Chippenham
Corsham
Malmsbury.
Assuming you're planning on state secondary, of course!
Both Ciren and Chippenham have got very good schools... Either Deer Park or kingshill are very good, not a lot between them!(Ciren) and either Hardenhuish or Sheldon (Chippenham) but not so much Abbeyfields.
Corsham School has got a good rep too, although don't know loads about it.
Likewise, I don't know loads about Malmesbury school either, but when I was looking for teaching jobs a couple of years back, I was told by some other teachers that it was okay, but that I could find nicer schools! I was told that the kids can be a bit rougher there at times!
Don't know if this is of any help to you, If not ignore it 