Well Fischer was
But as you say, that hardly covers everybody. The top players I've met are old names now. Walt Browne could be difficult to be around. Bill Lombardi was occasionally a poor loser. But any number of them were perfect gentleman. I saw Pal Benko lose to a player 2 classes below him with perfect grace as a for instance. Wasn't pleasant for Benko but he knew it was a big deal for the guy who beat him and he gave him a graceful post-mortem.
Paul Keres thanked me for giving him an interesting game (which he won easily enough) during an exhibition. Nothing remarkable about this -- Keres had been doing exhibitions for more than 30 years at that point -- but it sure made my day.