By Ivan Maisel, ESPN.com

Editor's note: Each week, ESPN.com asks one of its Heisman Watch voters to explain his/her picks. You can register your vote at 2008 Vote Heisman.

There have been seasons when the winner of the Heisman Trophy became indisputable in October. There have been seasons in which the player who should have won got sidetracked by injury or by too many losses. But rarely is there a season when voters could justify voting for any of the three finalists to win American sport's most famous award.

Whoever among the three finalists wins on Saturday night (ESPN, 8 ET), it will be easy to understand why the voters chose him. But a choice has to be made. Here's my ballot:

1. Sam Bradford, Oklahoma: Bradford is the most prolific quarterback in the game, whether the measure is easy to understand (48 touchdown passes) or hard (186.3 passing efficiency, an FBS-record pace). He drove the Sooners to the Big 12 Conference championship and to the BCS Championship Game. He has poise on the field rarely seen in college football, much less from a redshirt sophomore. He even supplied a Heisman moment -- that helicoptering leap that failed to score at Oklahoma State. He's also a 3.95 student, a scratch golfer, a former AAU teammate of Oklahoma hoop star Blake Griffin, and just when you've heard enough to start hating the guy, you should know that he's nice, too. Bradford would be a worthy successor to Tim Tebow.

2. Colt McCoy, Texas: If you like your Heisman winners as MVPs, then junior Colt McCoy of Texas is your candidate. With him, the Longhorns got nine toes over the threshold of the BCS Championship Game. Without him, they would be gearing up for an Insight Bowl against Minnesota. Exaggeration? OK, maybe a little. But McCoy has evolved into a talented passer (check out that completion rate to the right) and he has been the Longhorns' best rusher. More than anything, he has been a leader and a fighter. He pointed the way to victory over Oklahoma and he willed the Longhorns' comeback at Texas Tech. In the end, McCoy's stats, as impressive as they are, don't measure up to the production of Bradford. But I voted him second in recognition of one of the great quarterback seasons in Texas history.

3. Tim Tebow, Florida: Tebow has made a habit of being dominant at the end of the game. He did it last Saturday against Alabama, and he has done it in his attempt to become the second player to win consecutive Heismans. He closed fast in this race after a slow start. In retrospect, it may not have been slow as much as it didn't compare to his numbers of a year ago. But Tebow has been the consummate leader for the Gators. He has proved to be a deadly accurate passer. He remains a bull of a rusher. Only when compared to himself did Tebow's season finish second. I would argue that he is a better quarterback than he was a year ago. But in looking for a way to choose among these three, I chose Bradford's numbers and poised leadership over Tebow. McCoy's ability to carry a less talented team than the Gators to an 11-1 season won my second-place vote.

4. Graham Harrell, Texas Tech: Graham Harrell had another prolific season as the Texas Tech quarterback. The senior suffered in the Heisman race more because his defense could not cope with Oklahoma than because of anything he failed to do. None of Mike Leach's very productive quarterbacks has played at the level that Harrell has reached. None of them had Michael Crabtree, the sophomore All-American, of course, but Harrell did as much for Crabtree as the other way around. When the Red Raiders faltered at season's end, it cost Harrell a chance to be a Heisman finalist. He just made the mistake of playing his best in the same season as the quarterbacks listed above.

5. Shonn Greene, Iowa: In the Year of the Quarterback, Iowa junior tailback Shonn Greene is the best rusher, which is sort of like wearing a tux to a costume party. Still, no Heisman candidate came farther than Greene. After two seasons as a backup in which he rushed for a total of 378 yards and two touchdowns, Greene left the Hawkeyes in 2007 and went to a junior college. When he returned this season, he came back a transformed runner. Greene finished second to Donald Brown of Connecticut in the NCAA rushing race, losing by 93 yards. But Greene had 60 fewer carries than Brown. That average of 6.2 yards per carry put young quarterback Ricky Stanzi into a lot of second-and-4s.

Each week, ESPN.com's panel of experts casts its votes for the top Heisman candidates. The panel consists of analysts, former players, former coaches and ESPN.com's college football staff.

Votes: 1st place = 5 points, 2nd place = 4, 3rd place = 3, 4th place = 2, 5th place = 1.

For the complete list of Heisman winners, click here.