The winklebury one is pretty good, nicer premises at least. They tend to want £50 for b2b and this sometimes involves them naked and just standing next to you, however ladies like Wendy provide a very good b2b.
If you don't mind travelling to Newbury then Lotus Spa is reasonable. £30 for 30 minutes plus £30 for b2b. I've been a few times and only once was I disappointed with the masseuse on duty.