I have flown BA first class 10 or so times, on 777 and 747 and have never had a bad flight, one occasion was perhaps middling, but all the other times have been excellent, unless you become unbelievably picky (which I agree is a personal choice). The one middling occasion was more down to an extremely intolerant passenger in 1A who for some reason thought she owned the plane and was not happy that my wife dined in my buddy seat and talked quietly. I will say that generally I am a content person, which helps
I have not flown first with other carriers, but have been used to being spoiled with top level international hospitality during my career so do have some idea of quality to base it on. Each to their own and all that...but for me flying first is considerably nicer than Club (on the current seats).
I would add that the boarding could sometimes be better, it should be a cast iron rule that fist passengers always board first, without the scrum that can sometimes be involved.