I'd probably need my anime list to be completed to list all the characters precisely so I'll just list the characters I remember.
Maybe it's good to announce first that appearance really matters in my case.
Amber from Darker Than Black.
Not really my first, but I gotta admit I had a crush for her. No matter what Hei did to her in the anime she didn't change her mind about him.
Belldandy from Oh My Goddess! Yes, really. I was about 13 or so when I first saw her at an anime magazine. Back then I was fixated on stuff like this, goddess etc...
Nowadays I dislike characters like her.
Lenalee from D.Gray-man. Until they ruined her hair. After that I lost any motivation to watch this anime I had left.
Saber from Fate/stay night. By now it should be clear I prefer blondes. It's been so long I can't even remember the reason anymore.
Oh yes, before I forget. Miharu from Gasaraki. She didn't talk a lot. That's probably what attracted me.
Lilianne from Princess Resurrection. For the way she treats everyone else. Go ahead laugh as much as you want.
Yuki from The Melancholy of Haruhi Suzumiya. She only talks when she feels like it. And I'm pretty sure she's really popular out there.
Arcueid from Shingetsutan Tsukihime. Been too long, can't remember about the details. But it's definitely something to do with the fact that she's a vampire/blonde.
Miu from Linebarrels of Iron. Gentle, cute and great body. Her sister-like figure was also attracting, since I never had a sister.(She was the latest one so she gets the best praising)
Well that sounds pretty much like a listing. I'd love to go into details but, it was a temporary crush I had for them during the series, crush that was over once the anime ended.
So despite how I never really had a crush for any girls, it's still hard to believe that I left some characters out of that list...
Edit: I was thinking about mentioning her first but I forgot about her.
Mio from K-on. She's probably the youngest in the list and for the first time in my life (while watching K-on) I've felt like a phedofile (actually I have no idea how they feel, but if I had to guess that would be it).