I liked Maguire's Peter. But confident is something he wasn't often. He was still shy, still awkward, still a total dork to the point where there was a disconnect between him and the badass in the mask who beats up crooks and saves lives every day. It's unrealistic as hell to me that even by movie 3 he was still getting teased at school, parting his hair like a dork and going to dates looking like
this.
Enroll a shy kid in sports or drama classes and see how he develops. Put him in Spider-Man's shoes for a while, doing news-worthy stuff every day, and forget about it. Garfield's Peter (outgoing, quick-witted, confident x 10) seems dead-on to me. Too cocky too schmocky, I think Garfield nailed the character.