I know for service there is no doubt it would be BA (visitors seat, great for dining or meetings etc; choice of 45 video cassettes, bring your own if you want; fantastic food; seat reclines to 6ft 6in flat bed size; pre-flight dining if you prefer it).
I'm sorry but CO BusinessFirst is nowhere near that level of service - sorry but it's more like BA Club.
Anyway, I was thinking more about the mileage opportunities than the service.
That is my dilema, great service on BA, but better mileage earning opportunities on CO/UA.
MF