Hmmmmm.....I thought over my first answer, and I'm going to elaborate a bit.
I'm going to try to go through my options, and rate them out of 10 for how much I would want to date them, and how that would go.
Buffy: Buffy is lovely, but she has a type, and I'm not it. Plus she's super angsty, and very starcrossed. 5/10
Xander: Nice, but rather needy. Plus he fears commitment, and can be a jerk at times. 3/10
Angel: The whole curse thing seems like a problem....plus he always seems so miserable 4/10
Willow: Willow is adorable! But bad things always seem to happen to people who date her...IDK 6/10
Giles: Giles is actually really hot, and quite smart. But he's a bit too old for me. 7/10
Spike: Very attractive, and such a bad boy. Probably too much of a bad boy. 6/10
Tara: I really love Tara. She's so gorgeous and sweet.A little shy, but in a cute way. 9/10
Faith: Sooooo hot! God, I wish. She would be the best girlfriend if she maybe started going to therapy. 8/10
Anya: Not really my type. She's hilarious, but I would prefer her as a friend 3/10
Cordy: Gorgeous, smart and capable. Her personality in first and second season Angel is amazing. 8/10
Drusilla: I love my girl, but she would be.........a handful. 😂 2/10
Darla: Same as Dru, I think 2/10
Oz: Oz is cute and has an amazing personality! I love a good musician! He's so cool and funny. 10/10
Wesley: Wesley is incredibly hot! He is also really smart, and bookish like me. 9/10
Fred: Fred is actually the most adorable creature to ever walk this Earth. I love her appearance,personality, and accent. She's such a dear! 10/10
As gay guy- Larry. And I'd totally fawn over Spike like Andrew does.
As straight woman- Spike ...*cliche I know but he just has sexy charisma and he's tough, fun, hilarious & a romantic at heart - how can you not 😍 him?
As gay woman - I'd probably try to get Faith because she's a mix of butch & lipstick lez.. when she turned me down or got over me... I'd settle for Kennedy because she's also tough & femme but actually gay & proud. Tara's too soft & Willow is cute but too complicated.
As straight man - Buffy's ideal
From Buffy I think it would change throughout my life. As a teenager i think willow would have been a good match for me. In my 20s I think Anya would have been my best match given the type of girls I was attracted to then. In my 30s I think Jenny would be my ideal match. Now its probably Joyce!!! Lol. As a parent with a step daughter, the experience from that would help with Buffy. I'd definitely do things differently from Ted!!! Overall I'll go with Jenny.
From Angel I think my best match would be Cordy from S2 until birthday in S3. Just loved everything about her character and how she dealt with things. Plus she was so selfless, independent, confident but with a heart of gold. I do really like Fred but she's meant to be with Wes so couldn't get in the way of that.
Doyle hands down. He's funny and kind and empathetic, he acts as the bridge between Cordy and Angel when they just can't get each other but he's not a pushover - he's just a really good communicator. In his core he's pretty selfless - in his pre demon days all his work was around helping others and he's willing to sacrifice his life to save strangers and keep Angel fighting , which suggests he has more determination and dedication than is immediately apparent. He's brave (even if he doesn't want to be), you know he has your back but he isn't actually much of a fighter. In fact he isn't into any of the dumb macho stuff that so many of them fall foul of (Gunn and Wesley I'm looking at you!) - he is completely secure with the fact that Angel is taller and stronger and a better fighter than him, he's secure in his position as side kick (he's also secure enough in himself to laugh at gay jokes at his expense - and even make them - which in the gay hysteria landscape of 90s television is no small thing). He's impressed by Cordy when it turns out she can throw better than he can and he accepts without question or pause that of course Buffy is so much stronger and better equipped to fight the mohra demon than he or human Angel are (compare that to Riley's reaction to finding out she is the slayer - insisting that if she just gives him a week he can take her). He just isn't intimidated by other people's power, or made insecure because he can't match them - he gets that other people being powerful doesn't make him lesser and so is able to support them in what they have to do rather than trying to tear them down to make himself feel better. He's clever and has all this knowledge and connection to the demon underworld - including a reasonable amount of book learning (he recognises the gem of amara immediately whereas Giles dismissed it as a myth). He's obviously a bit of a romantic - he marries Harri very quickly and falls in love with Cordy very quickly. And he's just so cute and squishy! Clearly he is the best shape of all the men for cuddling up to (I've never dated anyone with washboard abs - but I assume they're not really that comfy for snuggling up against on the sofa, Doyle looks wonderfully soft and warm).
His only real problems are the self loathing, bad debt and mild alcoholism. He would definitely have to sort that out for himself before I dated him - because there's no fun in being someone's crutch - but he was already making big strides in the right direction in just 9 episodes. He could probably get it together reasonably quickly - and then it would just be a lovely, chill relationship with lots of love and laughter and very little angst or melodrama.
The only other character who even comes close is Oz - but he might run off with a lady werewolf or decide he's too dangerous to be around people at a moment's notice. Cue more melodrama than I am willing to put up with. I'm just too old for that s***. Plus I don't actually fancy him.