Matt Kenseth.
I've been pulling for Matt since I first saw him in a Busch race at Rockingham in ... '98? There was a caution with 30 or so to go, and this unmarked car pitted with the leaders. Most people the unsponsored car had to be a lap down and pitted with the leaders by mistake. Nope, he was on the lead lap and came out sixth or seventh. After the restart everyone was watching him pick his way through the field, working his way up to second. On the final lap, in turn three, he nudged aside and passed race leader ... Tony Stewart, who was running Busch as part of his transition from Indy cars. The crowd went nuts.
Five years later, Matt would lock up his (first?) Cup championship at the same track where he got that first Busch win, with a week left in the schedule. That's part of Matt's appeal to me; many of my memories of watching his early NASCAR career are tied to Rockingham, my favorite track.