I would've loved to see Yuuichi and Mai together, because he did care enough to talk to her and keep her from being this quiet and isolated girl. Also, the ball room dance was amazing. I thought to myself, "how could they not end up together?" But it does seem that Sayuri is in fact more than just a close friend of hers. Mai never shows more passion towards any other person in Kanon.
As immature as she might have seemed (which was my only turnoff), Ayu is definitely the right choice seeing as he clearly had more feelings for her than any other girl. If that kiss in public isn't proof than I don't know what is.