When I cosplayed as Anju from the Legend of Zelda last year, I had one girl run up to me and gush that I was her favorite character and asked me for a hug. She was SO excited that I gave her a hug and even more excited that I remembered her being a Link cosplayer from the year before. It really made me happy to make someone's day like that.
A lot of people really like my No Face cosplay, so any compliments that I get while wearing it really make me happy. I typically go to the rave as No Face and it makes my night when people are excited to come and dance with me. There's no real specific compliments that stand out more than others, but overall it's just the fact that the cosplay makes other people smile that makes me happy.