I haven’t flown enough. And I haven’t been to all the airlines. But my limited sample size has showed me that United is the worst airline. It’s not as nice as others. I’ve flown on Delta a couple times. I thought it was pretty nice (for an American airline).
My first commercial flight was in 1952 on an American Airlines Convair from St. Louis to Chicago. Countless commercial flights after that until I permanently quit in 2001. All the way up thru at least the 60’s most pilots were WW2 vets. After that, airlines hired heavily from ex-military pilots. This covered the “Golden Age” of aviation and everything worked like a clock. United and American were premiere for domestic business travel an Pan Am for overseas. Everything went to hell with new generations of woke management, pathetic junk passengers, government meddling, infernal TSA type stuff and general overall American cultural rot.