I would be Sarabi or Kovu, maybe Vitani, but I'd rather one of the first two. I also wouldn't mind being Simba.
I'd like to be Sarabi because she's well, she's nice and caring, but she's also strong-willed. She lost Mufasa and thought she'd lost Simba, too, but she still didn't cower before Scar or give up, so she's pretty awesome.
Kovu I'd like to be because he got all of that training; while I'm sure that was a bad life, he had a change of heart that left him happy with someone he loves. Having that training and being with someone you love's gotta be pretty alright.
Simba because ever since I was little I wanted to be Simba. My mom says I used to crawl around on my hands and knees, say, "I'm Simba," then ask my cat to go with me somewhere, addressing her as Nala, and the cat would follow.

Simba's just a cool character, though, so what d'you expect; almost everyone will probably pick him.
And well as for Vitani; for some reason I've always thought I could relate to her.