Riley and Cordelia? No. That is. No. Riley would not survive Cordelia.
Why?
For the same reasons that make Cordelia good for Angel. She's got moxie and confidence that Buffy simply didn't have at the time she and Angel got together.
Although I wasn't a huge fan of the Buffy/Angel relationship, especially looking back -- I do believe they were together. There are many different relationships - and given time relationships can change, though some do not and i do not believe theirs ever did. In my opinion, theirs was too on the surface to be healthy or longlasting, even before Angelus appeared. They simply are too much about ideals and romantic ideas of who the other partner was or 'should' be, and not enough about real. Romance is great for dates 1 through 3. Ideals are not surprising when you are 16 or 17. After that early rose colored glasses period, you must build something if you want things to last and progress -- several somethings, actually. Some of those are: friendship, communication, interdependence, negotiation and TRUST.
For a young couple, there also needs to be excellent sexual communication and mutual satisfaction. No woman in her late teens through her late forties (and most far beyond that) who is remotely normal will be able to deal with celibacy without unhappiness unless she's dedicated to something all consuming like the church. (Buffy showed herself to be a deeply sexual person, so she's not part of that small number of asexual or low sex drive people.) Waking up next to a sexy man she cannot have sex with is more of a form of torture. It could NOT work.
OK, Cangel.
While I liked their interaction much better - it was much more adult, and at the same time much funnier. It wasn't the grand romance, but there was so much love and affection there. Love that scene where he's teaching her to fight... hotttt.
I think Cordelia both changed for the better and helped change Angel for the better by challenging him to be his best self, not taking BS or putting up with his brood festivals... and finally, by dragging him kicking and screaming into the human world.
I am not as sure that Angel is good for Cordelia. He lies to her. He abandons her for his obsession to Darla. He almost gets her killed directly because of his choices. Since the existence of Jasmine in the world is directly due to the existence of his son, an argument can be made that he's also indirectly responsible for her being taken over by Jasmine -- but she chose to ascend, though a less vain person would have seen that for the trick it probably was. Why would she of all people be invited to be a higher being? Anyway, I digress.
I think Cordelia is good for Angel and for his mental health. She keeps him focused on the mission and keeps him in the world.
I don't think Angel is good for Cordelia after the first year. He is more concerned with his various obsessions, including his obsession with Buffy that never really leaves...
Yet, he also connects with Cordelia... but she ends up playing second fiddle. Which leads to years of mixed messages. She deserves more.
In the first year, they both change each other in positive ways. After that first year, most of the benefits go in Angel's direction. She continues to humanize him, to make him laugh, to keep him focused on his goals and she treats him with love, but never hero worships him. She becomes progressively less self centered and more concerned about the mission. Angel becomes more obsessive and more concerned about the 'reward'. He obsesses first about Darla, then his son, then eventually the years long obsession with Wolfram and Hart takes over in a final suicidal 'mission'. I believe losing Cordelia finally meant Angel lost his way for good.
With Cordelia gone, Angel becomes like Samson, taking down the "walls" around him. Never mind that there's people in the city/on the planet.
If I had to vote for one or the other, I would probably vote for Cangel over Bangel, but to be honest, I don't ship either woman with Angel.
Mostly, I ship Buffy with Spike or a crossover character (Two of my favorites are Daniel Jackson from Stargate and Teal'c, also from Stargate).
I mostly ship Cordelia with Angel's version of Wesley (post dweebiness) or Groo or even pre-Fred Gunn -- they had great chemistry and they had... fireworks! Or I ship Cordelia with Cameron Mitchell from Stargate. He is hot. He is smart. He has all the solid qualities in a guy that she would need, and also the world save-age gig and a sense of humor.
Angel? I mostly don't see him with anyone, at least not as he is. Sad, but true. I see him chasing the mission, too busy to really form a long term relationship, or do something about that pesky soul anchoring. Soul anchoring is a MUST before he gets a girlfriend (or a boyfriend).
Yes, I can see Angel with either a man or a woman. Someone who will not take BS or put up with the brooding. He's a good man.... pire, but he needs 'woke'. There are things he needs to deal with BEFORE he can be good to be with as a partner. Good FOR a partner. Any partner.
The only longterm ship I've actually ever put him in is with Xander Harris (yeah, surprised me too, but it was very satisfying to write). Xander because he's much too willing to call Angel on his stuff, to let Angel get away with his bad habits. Because Xander is angry enough to confront Angel about who and what he has been and is. Because Xander speaks his mind, even when other people would fear to! Just as he confronted Angelus in that hospital when Buffy was ill and he was terrified.
Angel is good for Xander b/c Angel demands Xander does his best... and because Angel is willing to spend money on Xander and stand up for him, something no one else ever has been willing/able to do... something someone starting out in life needs both financially and emotionally... Angel pretty much wants the people he cares about to do well, whether or not they end up with him in the long run - we saw this with Buffy -- he wanted her to have something 'better' than him. He challenges Xander to be more.
Angel is one of my favorite characters ever, but in canon I see him as a tragic character more than a triumphant one. So anytime he's in relationship with another, unless something changes from canon, I see something bad in the offing.
Buffy can get over heaven. I think she does. I think she can build a life with a man, including Spike... Spike is uniquely able to draw her out of herself, but I don't think he's the only person who could. She is profoundly connected to others, though she is somewhat of an introvert, she forms deep bonds and draws strength from them.
Cordelia is mostly a healthy person, though she needs to grow up and become less selfish, and probably to heal from being neglected by her rich, selfish, unavailable parents* -- getting a mission goes a long way toward helping her to grow into her best self. She's confident, she's a happy person by nature -- and she's also capable of forming a strong relationship with someone.
Bottom line: Between Cangel and Bangel? I choose... neither.
*We see Willow's mother. We meet Xander's horrid parents. We see both Buffy's parents, including the sperm donor. We even see Tara's father cares enough to collect his slave. Oz calls his family on the phone... he's in touch with them. On Angel, we see Fred's family, Gunn's surviving sister, Wes' father (and his mum on the phone), and even Lorne's horrid relatives. Hell, we even see Angel's own family (and Spike and Dru's as well, come to think of it)!!! We never see Cordelia interact with her family. I think that is telling.