Ria agrees with all this stuff! I've only gotten fanart once so far, it was a birthday gift from last week but I like just about lost it haha! Of course if I make a design myself I'm like 50% more attached unless the design is like FREAKISHLY awesome or from a rediculously amazing person, not that I could afford them.
I'm happier when I get fanart of an OC I made myself, because like you said, they like what I created myself. I mean sure, it's nice to get fanart from others of any of my characters, but there's a bit more spazzing when it's Comet, Blade, or Mei, or any other character I designed myself :3
Both for me, especially when they use the character's personality in the image, it makes the whole thing much, much better. Though i always will squee when i see pictures of Sea running around >w< she's my baby