From a book - Myron Bolitar from the Myron Bolitar series by Harlan Coben. He is immature, witty, and oh so perfect! Or Windsor Horne Lockwood III (Win), his demented, terrifying, bone breaking, killing, rich kid friend. Tough choice!
From a play - Rosencrantz from Rosencrantz and Guildenstern Are Dead by Tom Stoppard. He is sweet, very smart/philosophical, even if it takes him a little longer than most, and funny! I hated the way he was treated by his jerk of a friend, Guildenstern, because he enjoys life without over analyzing like Guildenstern!
Dean Winchester from Supernatural. Without a doubt.
Artemis Fowl without a doubt.