VSC
Having failed to commission after my legs gave way (ironic now considering my level of fitness 23 years on) I regret not being able to use the RAF Club. However, I've now been a member of VSC for nearly a year, and am using it this week again.
The refurbished rooms are superb, and the old ones not yet done have a sort of eighties mess nostalgia about them. The place is secure, you know what you are getting, and the restaurant and bar are fine too. Easy for Marble Arch for the Tube and shops.
I like being able to turn up in the Smoke, knowing what I am going to get, for a pretty competitive price. Gets my vote every time. Never tried the UJC, and was always a bit reluctant being south of the river.