Me-TV recently broadcast the M*A*S*H finale. Though I enjoy many of the Mike Farrell/Harry Morgan/David Ogden Stiers-era episodes, I feel this show is stronger with McLean Stevenson and Wayne Rogers and the ending of its storyline is much more effective than the show's finale.
Seinfeld is my favorite television comedy. Its finale is an abomination.
The Sopranos - to me, an epic motion picture serialized for television - is among the finest work of art yet produced. Its finale is clumsy.
I forgot about the finale of The Mary Tyler Moore Show, which may be the best.
Here's why I've posted about this:
http://www.bbc.com/culture/story/20150526-what-is-the-greatest-tv-finale