Sean Mannion has gone from a sure-fire mid-round to a borderline draft pick at this point in time, and for most teams that will hold true. There are some issues that will make it tough on him (mechanics and footwork for example), but I believe there are a couple teams that will be a better fit for him.
This is based on a lot of situations, but my view focuses on scheme and quarterback situation. For example a team with a sturdy starting qb who improvises like Philip Rivers would be a terrible fit. Mannion needs a situation where can be either mentored or else he needs to be a strong schematic fit.
The first team that might actually work for Mannion would be the New Orleans Saints. With Drew Brees in front of him he clearly would not be seeing the field anytime soon, but he could learn from one of the top pocket passers in the league. There is even a precedent set as the Saints once drafted Sean Canfield in the 7th round and stayed with the team on the practice squad until he ran out of eligibility.
Also important is that there is no heir apparent to Brees in New Orleans. The current backup is Luke McCown, who isn't even the most well-known McCown in the NFL. This is a plus over teams like the Broncos or the Patriots. Despite the chance to learn from Peyton Manning or Tom Brady, they already have back-ups in Brock Osweiler and Jimmy Garoppolo. That will clearly significantly lower his chances of sticking with those teams. One more advantage is that he already worked with Brandin Cooks, who appears to be a large portion of their future plans.
New Orleans would be a pressure free spot for Mannion to develop and begin to learn. Perhaps how to read the field more quickly, how to get his feet set when he throws, or acquiring more pocket presence. As we've seen with other quarterbacks transitioning to the pros it is extremely difficult to change mechanics at this point in their careers, so that seems unlikely. Mannion might benefit from some time on the bench and learning from one of the best quarterbacks in the league with a receiver he is already familiar with.
There is one more team that should take a long hard look at Mannion though and that team is the Arizona Cardinals.
Arizona is lead by coach Bruce Arians and his quarterbacks have been a very specific type, which is a quarterback who loves to chuck the ball downfield. The current Cardinal roster shows that goal as well. Carson Palmer is the starter who is still working back from an ACL injury, but was a pocket passer with enough arm to try and throw deep to Michael Floyd. Drew Stanton is not as good but still made the team decent, until he was hurt. The last two quarterbacks, Ryan Lindley and Logan Thomas, were wildly incompetent and could be beat out. Arians knew what he wanted out of his quarterbacks though and they all had strong arms with the willingness to throw deep passes.
Coach Arians has mentioned in draft interviews how he wants someone with a pro-style background and Mannion again fits that. From a player standpoint they are solid weapon-wise with Michael Floyd, Larry Fitzgerald, John Brown, and safety plug Andre Ellington. The run game is mediocre, but the Cardinals showed last year they need a quarterback and quite honestly Mannion has a chance to be just as good as any of the rest of the qbs that the Cards may have.
He would have a genuine shot at starting and the receivers could actually snatch the ball when he forces it into tight spots downfield, which he seemed always willing to do for much of his Beaver career. He will obviously still need to develop his skills and mental game, but this seems like the most advantageous spot for Mannion to land, hopefully the Cardinals agree and take a late chance on Sean Mannion.