[Firewire]

Best:
Breaking Bad - yeh
Buffy the Vampire Slayer - yeh
Cougar Town - one of the best finales I've seen
Glee - it has been a mess since season 2 but the finale was great in ending character's individual stories
Parks and Recreation - I liked the style of the episode and it rounded up each character
Ugly Betty - it was pretty perfect but was ended far too soon. Very underrated show.

Mediocre:
Angel - felt unfinished, but it was axed without warning
Community - same as above really
Desperate Housewives - the last season was a bit of a mess overall and of course it was all about Susan!
Friends - should've ended in season 8, plus Rachel should've went to Paris
Gossip Girl - underwhelming
Revenge - it was a bit meh, wasn't it?

Worst:
How I Met Your Mother -

Spoiler:

the last season was enjoyable but the finale was written in 2006 so it was a bit strange. I didn't like the way it showed certain characters futures because it was out of the ordinary. They spent a full season on a wedding and, well, if you've seen the finale it makes the whole ninth season null. It had a good end for two characters though.