Well, either way it season 2 or 5 and I’m gonna go with season 5 because it always felt a little strange that Team Angel started working with Wolfram & Hart and it changed the whole vibe of the series.
Also, my favorite female character Cordelia doesn’t appear (except that one time) in it.
I did enjoy Spike joining the Team and the cross overs with Andrew though and there are some great episodes after all.
(This episode is probably also my favorite season finale.)
Great story line (it’s all about Team Angel being threatend, that always makes great episodes for me) and a happy ending (at leats for the short term).
But as I’ve already mentioned, season 1 features many great episodes such as …
I will remember you - possibliy the saddest and most heart-breaking episode in the whole Buffy/Angel univers. Still, the little glimpse of their shared future is thrilling.
She - is a cool episode with a important meaning but the best about it definitely is the Angel dancing scene (very closely followed by Wesley’s) which is one of my favorite scene on Angel of all time.
The Ring - it reminds me of the movie ‘Fight Club’. And as much as I condemn violence in real life, the idea of ‘The Ring’ is really fascinating.
Eternity - this episode also features on of my favorite scenen on Angel of all time, namely when Angel turns into Angelus and mocks Cordelia’s acting skills (and then crashed down the elevator shaft). Watching Angelus is generally a pleasure.
Five by Five/ Sanctuary - Faith is one of my favorite Big Bads onBuffy and so I still love watching her on Angel, too. Plus, it’s a really exciting story line, plus I like all the cross overs they made in season 1 (and the following). Still, Angel the series was different from Buffy the series and that’s a great thing.
War Zone - Gunn will become one of my favorite characters, so it’s great to see some of his past and how he met Team Angel. Plus, again, a really interesting story line.
Some time ago, I started to write a list of the books and movies I read and watched during the years. So, I checked that list and according to it, season 1 is my favorite.
I’m currently rewatching season 1 and I’ve noticed how many times I laugh. I think I remembered that the later seasons weren’t that funny, they were a lot more serious or at least the atmosphere was - because Season 1 is really serious too; Doyle’s death, Angel loses his humanity, Faith, Cordelia getting the visions, …
Season 1 also has more favorite episodes in it than the any other season.
I also wanna write a few words about the other season:
Season 2 - The main antagonists (Darla (!), Drusilla and Wolfram & Hart) were entertaining to watch but other than that I can’t remeber a lot anymore …
Season 3 - I think this season is (together with season 4) the most heart-breaking and hurting (mainly because of Connor). The season finale was the worst ever, as I recall.
Season 4 - On my movie list I commented this season with “Holy Moly” (as I did with season 6 of Buffy). It’s painful to watch my favorite female character getting screwed up. Actually, I felt the wole season was painful to watch but still fascinating and thrilling. And I loved watching Angelus coming back, I really enjoy watching him.
Season 5 - I watched the first half of this season and then made a break for almost a year. I watched the second half of the season within a week, so I don’t know if the break is a bad sign or the “within a week thing” a good sign. This season felt a little off because Team Angel was now working with Wolfram & Hart. The Scooby gang and Cordelia thought the same. Though in the end it did make sense again but I don’t think Angel knew that at the beginning. Spike was a great addition to Team Angel, I loved him. The season finale is (as I read in Joss’ comment) a statement - but it’s also a cliff-hanger.
I would say, season 1 as my favorite is followed by season 4 and 3.
But I love the woman Cordelia became on Angel and I think she was a real and true friend to him. She supported him on his long and difficult journey - Doyle’s death, Darla’s return, becoming a father, losing his son, losing Buffy, losing the right path … And they completed each other.
I think she was the best friend he could have ever wished for!