7. Season Four
The weakest season of Buffy the Vampire Slayer is still pretty strong. "Hush" and "Restless" are two of the series' most daring and beautifully executed episodes, and the introduction of Spike as a main character turns out to be a great gamble. The return of Faith Lehane is also something special, and a return many fans were excited to see. Her two-part arc is one of the best of the season.
All of this aside, Season Four doesn't have enough Faith or Gentlemen to keep it afloat, as it finds itself weighed down by many things. Riley Finn and the Initiative, for example, start off strong but get tedious quick, and the loss of Cordelia Chase, Angel and eventually Oz as main cast members hits the show hard.
Episodes like "Superstar" and "Beer Bad" are hilarious but unnecessary, and Oz leaving Willow is devastating and cruel given the potential of his character. The less said about Adam the better, though we'll concede he sounds promising on paper.
Tara Maclay is a fantastic addition to the show, though, and Spike and Anya bring a level of sarcasm and pessimism to the show that left with Cordelia. This is still Buffy, after all, so there is a lot to love. It's just a shame there wasn't more of it.