It's funny really; my taste in lovers is way more diverse in anime than it is in real life. We've got practically all the bases covered here.
L (Death Note)
Super-intelligent, super quirky, quite attractive and fascinating to look at. And of course, unattainable. For some reason, knowing you could never have someone in their universe, even if they're fictional, is just... heart-rending!
Spike Spiegel (Cowboy Bebop)
I'm not normally the type who looks at the "too cool for school" types, but he's so sweet and smooth! And when he's not chasing a bounty, he's kind of a dink. He's gorgeous and classic, with a strange kind of grace while fighting.
Saitama (One Punch Man)
I'm typically all about brains, especially when you've got a choice between brain and brawn. But Saitama isn't stupid. In fact, he's a pretty great social-psychologist. But he's not really book-smart, and that's what's so strange about me liking him. There's just something about his fun-loving spirit that makes up for any flaws he might have on my in-real-life checklist.
Mila or Rachnera (Monster Musume)
......don't ask.... D'em kinks, y'know.
Mugen and/or Jinn (Samurai Champloo)
Again, Mugen isn't really book-smart, and he's a little more hot-headed than I would normally appreciate, but he makes up for it in quirkiness. Jinn, on the other hand, is brilliant, quiet, and quite refined. If I could only have one, I would choose Jinn, but they both have their very strong points.
Those are all the anime characters I can think of for the time being.