The most likely Jet quarterback to win the starting job is sadly, Mark Sanchez. The 26 year old was a turnover machine last season, but with his heavy salary will be on the team. I think with Marty Mornhinweg and the west coast offense coming in, I think John Idzik and Rex RYan give the former #5 overall pick a chance to start.
If Sanchez falters in the preseason and loses the job, I think the guy who would replace him is veteran David Garrard. The 35 year old last played in 2010, when he threw 23 touchdowns and 15 interceptions for the Jaguars. Garrard knows the game and is a good veteran leader. If healthy, I really think garrard will give Sanchez a run for his money.
While a lot of Jets fans would love the rookie to start week one, I don't see it happening. i think Geno will be a franchise quarterback, I just think the Jets will let him learn for a year behind a veteran like Garrard or Sanchez. With not many weapons on the offense, it may be a good idea for Geno not to be thrown into the fire as a rookie.
The two other guys competing for the job are Matt Sims and Greg McElroy. Both are guys who may not make the team, and are more backups. McElroy impressed Jets fans last season in his one win, but faded after thats. Matt Sims, the son of Phil, was un-drafted and lacks the tools to be a starting NFL quarterback.