C/A - Could've been great, but wasn't. As soon as they introduced "kyerumption," everything went downhill, IMO. And Cordy trading in her wonderful b!tch-with-a-heart-of-gold personality for that of a generic female protagonist definitely didn't help. Part of the appeal of this 'ship is that Angel enjoys being the male half of a heterosexual power couple (as we saw with Bangel, and Angel/Darla), which requires hooking up with the alpha female. Cordelia could've been the ultimate alpha female had she retained her style and attitude whilst also making the transition from girl to woman. Sadly, about two-thirds of the way through AtS s3, she lost most of her personality and became a somewhat boring, watered-down version of herself. And since Cordy wasn't as interesting as she should've been at that stage, neither was this 'ship.
C/X - They had their moments, I suppose, but love/hate 'ships don't do much for me. That, and he cheated. And I don't think Cordy was wrong for leaving him permanently. (Though I think it's unfair to say she didn't forgive him. I thought that was the whole point of their subplot in The Prom.)
C/G - He's handsome and adorable and worships her. Too bad he came along at the wrong time in her life.
C/W - They're kinda my guilty pleasure, for the most part, but I do think that their relationship could've become a bigger part of the 'verse, had it been handled right. I especially love the idea of Wes developing an interest in her and trying to help her understand her demonization circa-s3, while her feelings for Angel are just dawning on her. Could've been a great storyline, and would've provided a nice parallel later on, as Wes basically becomes Angel 2.0 and then hooks up with Lilah, who is the evil/shadow version of Cordy.
C/D - They could've been a great couple, too, but I'm more or less content with him dying as early as he did. It's just one of those big things that I could never imagine rewriting.
C/other - Much like Lilah and Faith, Cordy's the sort of character I could pair with practically anybody, if for no other reason that it's HOTT. Which is what fanfiction is for, I suppose.