I would say the food is better in the Flounge, though the breakfast buffet has tended to run out and not be refilled often enough on some of my visits. Also noticed on previous visits that the wine is sometimes the same in both lounges (self-pour bubbles aside). Agree the LGW Club lounge is of a pretty good standard which narrows the gap, but except in cases of overcrowding, I'd still turn left.

Personally I would take the LHR Flounge over the LGW equivalent anytime, everyone's different.