Angel was, is and always will be my favorite character in anything and everything I've ever seen.
When his series began, I knew nothing of his time on "Buffy" and everything about who I was seeing - the sitting in the dark alone, the clothing, the inability to talk to people, just everything was like looking in the mirror, only Angel doesn't reflect and I look nothing like Boreanaz, who let's face it, is one beautiful man as mentioned by Oliver the Hollywood agent in "City Of", the pilot episode.
As I mentioned in a thread I started, I freely admit that because I'm not blind. There's nothing more to it than that.
Anyway...as the series progressed, I saw him grow and develop his own unique family unit, something I never really got to do (unless dogs count) and every struggle he endured, I felt for him deeply. He was why I tuned in. He was why I started watching "Buffy". It kind of saddens me whenever I see people say they never liked him much, or compare him to Edward Cullen (which makes little sense to me, since the little I know of that "Twilight" nonsense makes Cullen a creepy stalker type who lures and controls a girl, and Angel only provided Buffy with valuable information and fighting assistance, and their pairing was more natural and neither one had any control over the other) or the ever-popular 'Spike is better!' thing. Ultimately that doesn't matter, but people have this need to say one thing is better than the other and make the other inferior in some way.
Angel, as a series and as a character, mean the world to me. Escaping into his adventures on both shows meant making real life stresses more tolerable. That's a big part of why I watch "Buffy" as a series now - watching that group takes away the isolation. Angel taught me to see the upside to that isolation when he made it his own choice. As much as I love the side of him that strives to do what's right, there are times when I love his brutality - just because he knows it will hit a point home hard like his "merciful" act in the season 5 premiere 'Conviction', where he kicks Agent Hauser's shotgun up and discharges it, blowing the man's own head off and leaving a wounded agent watching in shock alive - the last act of mercy. Agree or disagree with his methods and choices, it's very easy to understand WHY he makes those choices.
Some of my favorite moments are:
-being lead around by Cordelia like he's some college trophy, which is even funnier in hindsight considering some two years later they'd be working together every day
-realizing he dresses like a vampire stereotype (Lie to Me)
-being frightened by Buffy as she sneaks in her own window, and he's holding her stuffed pig Mr. Gordo (What's My Line)
-meeting Wesley for the first time, which like Cordelia is very funny in hindsight. This meeting is so uneventful and brief, that's why it's so funny after the fact. (Bad Girls)
-Sense and Sensitivity...the Hawaiian shirt, the group hug, the 'magic word', the 'painbow'....'nuff said.
-getting shot, which just pisses him off (Expecting)
-"I don't dance" (She)
-Angelus...high as a kite (Eternity)
-Angel Vs. Riley, and unleashes vampire hell on the good soldier boy (The Yoko Factor)
-Standing outside looking at the night cityscape (Blind Date)
-not wanting to wear a pink helmet, getting called a gorgeous "Wanker" and getting looked up and down for wearing that helmet by a vampire (First Impressions)
-Mandy and Wang Chung...'nuff said.
-Redefinition...from the training to the sewer fight (my all-time favorite fight sequence of either show)
-Getting a fake tan (Belonging)
-being surprised at his own hairstyle, and showing great concern for his leather coat (no wire hanger!) (Over The Rainbow, Through the Looking Glass)
and many, many more from later seasons but this chronological list is too long as it is.