First rule about vegan flight club is bring your own food. I have been traveling while vegan for years and the best solution is simply to bring your own. Never disappointing this way. Is it a pain in the ...? Yes. I have an insulated bag packed with ice in a ziplock that has to be dumped at security and then refilled at the club. I also enjoy the looks of the first class staff when they come for my order on a 14 hour flight and I say "No thanks, I have my own". I am surprised that more people don't bring there own to avoid issues. How many people can remember an airplane meal that was better than a Friday's or even an Applebees? I am sure there are some exceptions (yes that means you SFO777. lol) but who wouldn't rather have a California Pizza Kitchen meal than plane food?
As for airlines that get it right, Thai's Asian vegan meal in first was very good. Salad to start followed by cold soba noodles in soy sauce and a main of jasmine rice and veggies in a spicy sauce. Dessert was a fruit platter. Worst vegan meal is a tie between Singapore in first where the second meal was some sort of unidentifiable patty in a sandwich, and Copa Business which served a warm cucumber burrito thing. Never heard of warm cucumbers before or after.
Bottom line is if you want a good meal on a plane bring it yourself.