i really cant shoose between the five, but I can tell you what order.
I loved:
Season 4 and 5- they are tied
Season 1
Season 2
Season 3

I loved season 4 because of the magnificent and brilliant ANGELUS! then five because of the rivalry of spike and angel.
Angel- "I've always like to your poems." to spike? he he. that was funny.

Then season 1 because of I Will Remember You. That episode was so moving and I liked how Cordy always made fun of Doyle and Angel's broodiness. lol

And, I dont know why season 2 and 3 are at the bottom. I think because I didnt like "Cangel". it just didnt sit right with me.
Anyways thats my list. Its hard to decide.

Angel Season 4 - The Apocalypse Was Just So Epic, More So Than Ever Before
Angel Season 3 - Lots Of Good Unique Episode, The Howl Connor Kidnapped Thing Was Annoyin Tho..
Angel Season 5 - Lots Of Good Different Themes From Comedy To Death [Fred :((]
Angel Season 1
Angel Season 2 - Just.. Meh...

Season 5, I absolutely love the whole season. It's just so massive, they kill off three major characters in the second half of the season and the introduction of Spike makes for some classic moments with Angel. The thing that always gets me though is the speech at the end of 'Power Play'...of course Spike's hand goes up first, that's exactly how he'd wanna go out, "kill 'em all, burn the house down while we're still in it"...the when Wes raises his hand and the music just changes slightly, man I'm such a sucker for hero stuff. When Wes says "I'm in", the look on his face and the tone of his voice, he's just so proud to be doing what he's doing, making Fred's death matter.

After S5 though it goes:

Season 2
Season 1
Season 4
Season 3

I actually think the first and last seasons are the only ones with top-notch finales, really don't like anything about Jasmine.

/\/\/\WHaaaaaT?


Season 1 Finale, Oh Great We See A Box Lol.. Who Cares About Darla She's Just A Pain In The Ass (BIYCH!) She Could Never Be Fred Or Cordeilia

Season 3 Had A Good Finale (Underated Season)

Coredilia Becomes A HIGHER POWER !!! *GASP*

And Angel Gets Sunk To The Bottom Of The Ocean (BY HIS OWN SON!!! *GASP PT 2!!!*)

Season Five [Spike and Angel in the same show, need I say more? Only thing it needed in my opinion was Cordelia.]
Season Two [Loved the Darla/Angel storyline, with the flashback episode Darla, return of Drusilla, and the beginning of Angel's feelings for Cordelia.]
Season Three [Wonderful season for my favorite Angel pairing Cangel, plus, I love how Darla gives birth to Conner, whole episode is heartbreaking.]
Season One [Great start for a wonderful show, loved Doyle, wish he hadn't left so soon.]
Season Four [HATED, this season. Worst season ever. The Jasmine storyline is the worst storyline of ATS ever.]

The Season One finale is brilliant, not for the fact that Darla comes back in a box but just for the whole episode. We see just how much Angel has started to care about Wes & Cordy, his apartment blows up, he shoots Kate down and then the final fight is brilliant - it even has a standard window entrance! Then Lindsay gets his hand cut-off as well, and without that we wouldn't have the brilliant moment in Season 2 where her grabs Lyla's ass and blames it on the hand!

The Season 3 finale was pretty poor, I don't dislike the season by putting it last, I just don't like it as much as the others. I loved the whole Wesley betrayal part but I did see Conner much in the same light I saw the Dawn saga over on Buffy. Don't get me started on the whole Cordy as a higher power thing though, that was totally lame...then where they went with it by giving birth to Jasmine made it worse.

I do like Season 4 up until Cordy gives birth to Jasmine though, after that it's barely worth watching. Evil Cordy was pretty hard to take as well...Charisma just isn't very good at it to be honest.

What's funny about Angel seasons that while overall Buffy is my favorite of the two shows, if you were to combine all of the seasons together, my single favorite of all 12 seasons would be Angel season 5. I think it was so good because a lot of elements came together, including Joss having much less to do to. So the focus was so amazing. It was a true tragedy that the show ended when it did. I HATE HATE HATE the second half of season 4. It was the most half-assed and sloppiest Big Bad ever.

Season 5
Season 2
Season 3
Season 1
Season 4

In oder it would have to be..
Season5
Season4
Season2
Season3
Season1, but all are great seasons..:)

In order and why...
Season 1 because it was the start and I love Doyle and Wesley! I just love Doyle and how Wesley was such a dork when he first appeared. :P
Then...
Season 3 Because the storylines are awesome I think, well up to the part when Connors kidnapped then it was as if the show itself was lost. :S But yeah.
Season 2 I just love Angel's dark side, but I'm not huge for Darla so that's why it's not the top of my list. lol if it wasn't for her it'd probably be my top fav season. :)
Season 5 because Angel and Spike were just funny and I love how they got along in the end, they're like brothers you know? and also I love You're Welcome! Oh man I love that, Cordelia, and also bringing in the memory of Doyle! It was the whole family the entire team was in that ep! even Lindsay was back. lol
Season 4! It just eeek. I just don't like that season AT ALL. The only thing I like are those three eps of Angelus and Faith, that's it! other than that! ugh! I love Awakening too! but yeah everything else, ugh! lolll