I voted Xander, because they were so cute with each other! They bickered like an old married couple! 🙂 How adorable. Maybe if Xander and Willow hadn't of kissed in Lover's Walk, Cordelia never would have went to LA! Who knows...
I also think Angel is good for Cordelia, but in a different way. It's hard to compare BtVS Cordelia and AtS Cordelia. They're so different, even though its the same person. She grew so much. So when she's older, Angel is good for her, but Xander was good for high school Cordelia. I'm not exactly sure if that makes sense, though.