The Buffy finale is not generally considered a cliffhanger, but the writers have explained why they do not view the Angel finale as one:
"The word 'cliffhanger' is really a misnomer here. This was not the final grace note after a symphony, the way the Buffy finale was. We are definitely still in the thick of it [at the end]. But the point of the show is that you're never done; no matter who goes down, the fight goes on. Did I end it this way so that it could lead into an exciting sixth season? Yes, but this is still a final statement, if that's what it needs to be." (Joss Whedon for TV Guide, 2004)
"The point of Angel was always that the fight never ends. He'll always fight. It's an eternity of fighting. You can't ever win but the fight is worth fighting. That was a perfect 'going out' scene... Any proper resolution of, 'Oh, we've defeated the demons, they've gone back to hell, let's get a beer,' just would have been absolutely wrong for that show." (David Fury for Meanwhile... The Blog, 2005)
"That ain't a cliff. I understand why people would want closure, but for me, that would be like adding a cliff note to the end. What I always wanted to say is, trying to become worthy of the life that you have is a life's work. The fight is for always." (Joss Whedon for Entertainment Weekly, 2019)
Both series continued in comic form, but even the comic finale could be considered a cliffhanger by some standards. It ends with the same message from the Buffy finale: we fought and the world changed, now that we survived we continue to live. The "cliffhanger" is that there is always something next; a fight or life itself.
