This list will change day-to-day, but as of today, these are my top 10 among all episodes, with VERY honorable mentions going to: A Mid-Winter's Night Dream, Breaking the Ice, Moon Dance, Beware of Greeks, RDWRER, Out With Dad, The Show Must Go Off, Juvenilia, Wheels of Fortune, Star Mitzvah, Freudian Sleep.
It's my opinion seasons 2 through 7, 10 and 11 were better seasons in general and it made it too difficult to choose ten out of all episodes, so I chose the best one from each season, omitting season 6 because it contained the fewest "favorite" episodes among all seasons, but of course was still great.