It's a no-brainer: go to Old Sarum.
The standard of instruction is excellent
, there's a good club atmosphere, an interesting fleet and open airspace. Also, it's a licensed airfield so (although it MAY not be relevant in your case) there's no pseudo-legal ferrying before a lesson can start.
Visit all the airfields before you decide. Chat to the members and staff, ask to be shown the aircraft, discuss what training they think you are likely to need - then make up your mind. Don't pre-pay because it'll then be harder to move if you find you've made a mistake.
Edited to add: another consideration is the type of aircraft you want to learn in, or migrate to. OS has a large number of PA28s, a couple of Arrows, a couple of Bulldogs, a couple of C152s (one tailwheel), a Cub, a Seneca and a few C42s. Shadow and flex-wing instruction is also available on the field.
HFD