I find the LGW experience and levels of BA service, both in the airport and on the LGW based flights, to be generally great and just as good as LHR.
If a choice of LGW or LHR departures is available then I choose LGW every time it is practical. Why? It's not because of any preference of levels of service, but because my connecting flight from France arrives at LGW and I prefer the simplicity of connections rather than spending/allowing so many hours of my journey getting around London to LHR!