Why do so many people like Angel & Cordelia as a couple?

I love Cangel, for a lot of different reasons. I mostly love how their relationship grows. First, they were co-workers, then became friends, and then best friends. They had absolute trust in each other, and they understood each other better than anyone else. They were basically family. Slowly, that grew into something more and they fell in love. Some people don`t really see any romantic chemistry between them, but i saw it even from season 1.
One thing i love about them was that they brought out the best in each other. Cordelia brought out Angel`s humanity; he didn`t always have to be super-broody all the time, he could smile and laugh and be a champion. And same goes for Cordy, she was a much better person than in Buffy, and a big part of that is because of Angel.
I really find their story beautiful, i love the idea of love blossoming out of friendship, but of course they never go to be together. I think they would have been great together, but that`s my opinion, anyway.
There`s a lot more reasons but that`s pretty much the basis of why i love them together. Other people might have different answers, but that`s how i feel. I respect everyone`s opinions. :)

as much as a like angel and Cordelia as a couple I do have to admit that if they had continued the series with them together I think it would have ended up being quite boring. its just them together was too perfect and I think after a while their relationship would have loss its intensity

They really started as a very strong, and long-term friendship. They also saw each other really grow over time and become older and wiser. That's really the appeal of their relationship, to me. They have seen it all and have a strong connection together. And I feel the best relationships start out as friends and grow to more. :)