CyberPunk 
I didn't really consider Kimimaro over the others because he's pretty much a clone of Haku to me. They were both lonely and rejected because of their powers, and found happiness in being used as a tool later on in life (by a villian, no less). The only difference is that Haku had to experience the pain of losing his family, Kimi was probably glad to be rid of his. I also never got the impression that Kimimaro was very bothered by all the stuff in his early life. He just kinda took it all in stride, and was more frustrated and confused than traumatized in my opinion. The two's pasts were pretty similar, and both ended up feeling "useless" to the ones they admired, but Haku also had to deal with his family being killed. I can only really sympathize with one of the two - so Haku gets my vote.
Neither of the two match up to someone like Gaara or Sasuke, though, who have experienced loss yet have never found any peace in their lives. Both Haku and Kimimaro had found happiness by the time we caught up with them. They had found their reason to fight selflessly for another, and be content with their lives. Sasuke...well, Sasuke's character is completely based on the fact that he's utterly consumed by his past. It's turned him into a selfish, power hungry asshole who'll do anything for revenge. Even when the guy tries to be happy, he's haunted by the fact that he's not doing enough to exact his revenge on Itachi.
Lee and Neji have had shit lives, but comparitively better than the above characters. They're struggles were mainly based on limitations they had to face, but haven't had to experience loss or isolation to the degree the others have. They're also reasonably happy atm.
So really thinking about it, I'd say:
1. Gaara
2. Sasuke
3. Haku
4. Naruto
5. Kimimaro
6. Neji
7. Lee
