monica seles is the best loser ever... but hey, didn't happen very often, now did it? i don't remember anyone ever being as consistently graceful.
lindsay has said some catty things but she's usually pretty good.
dementieva always seems to have things to say in her defeat. it's also credit to her because she has to deal with SO many questions about her serve and her mental fortitude after every loss and she never really deflects it or says bad things about her opponents.
myskina- can't think of anytime she wasn't graceful, maybe i missed it.
sharapova- she never makes statements that she played like crap when she loses, but she does fall back on her age frequently i suppose. but it's always in a way where she's saying "i'm only 17, i have some things to work on. this was a good experience because now i know what to practice and how to gorw." as opposed to "i played like crap, otherwise i would have won." she never disses anyone. i think maria needs to be mentioned because she's under sooo much scrutiny right now, and as far as grace and composure are concerned, she gets high marks.