I don't think this is a complicated question to answer based of talent and NFL projections, the difficulty is in assessing any individual player's feelings about school or financial situation. Not knowing either finances or personal feelings I say this.
Descending order of draft value:
1-Marcel Dareus - Plays a very valuable position & a position of need. Some say he hasn't produced, I say bologna! His stats were better than the starters stats last year and without looking at this years stats I'm confident they're similar to last years. Take into account his nagging injury situation and having very little help along the LOS, scouts are drooling. His measurables are off the chart for a 3-4 DE as men his size aren't supposed to move the way he does. There are only 2-3 DL that could truthfully project higher than him in the draft depending on the team. A top 15 pick.
2-Julio Jones - Great year, matured, routes and hands improved this year. You simply aren't allowed to drop passes in the NFL. Pre season I figured how well he caught the ball would determine wether he went 10th or 25th & still feel similarly. I think he winds up in the teens, high or low it's just a guess anyway at this early stage. Again only 2 or 3 WRs teams could possibly be valued more than Julio, I expect Coach Saban to RAVE over Julio's work ethic etc. to scouts. One concern is it does in fact take him a few steps to get going as compared to other wideouts. He'll need to prove to scouts he can get off of top flight press coverage and be VERY physical in workouts.
3-Mark Ingram - A special talent for sure. However as the NFL has become more of a passing league RBs are devalued with few making the first round and fewer still making the top half of round 1. The backs that are taken high tend to be multi-dimensional (KR-pass catching machines-rush for big yards in top conferences - CJ Spiller types). Much of this works against Mark, but at the end of the day when the film is put on Mark Ingram has amazing vision, hips, power, pad level, quick feet, runs behind his pads well, body control, makes defenders miss in tight space as well as open space, EVERYTHING you want in a ball carrier plus is a high character guy coming from an NFL family. I figure somewhere past pick 22 and maybe the early 2nd round. Many teams will simply wait to pick up RBs as all-pros are routinely picked in rounds 3-7, but someone will place the proper value on his top 20 type ability and bite.
4A-Donta Hightower - Hard to believe but before the knee injury he was physically more gifted than Rolando, would have killed at the combine becoming another top 10-15 pick due to numbers. However his production just hasn't been great this year and he didn't shed blocks as well as a MLB needs to. Also his recognition wasn't there from time to time. (as a side note I hope CJ Mosley takes over the middle LB spot and Donta gets to slide to his old spot it would be GREAT for the team & him next year). He could possibly slip into the first round if he interviews well and test well in Indy, but he'd be best served coming back as he's probably a 2nd rounder.
5B-Mark Barron - Overall had a very solid year and was the QB of a very very inexperienced/young group that eventually led the nation in INTs. I don't think he'll test well in terms of speed, perhaps a high 4.5 for an NFL safety isn't special. It showed this year in a few spots. Overall athletic ability is top flight though and it shows when the film is put on. However his value as a quality player is still intact and next year he'll not be asked to do as much in the D scheme which will allow his play to 'appear' better and allow him to challenge for first round draft status. As it is now I have no idea of where he'd be valued, certainly high for his position but overall probably in the bottom half of the top 100 picks.
Others:
IF... IF Courtney Upshaw had a big year without the injuries he might have been a surprise to jump ship, but I don't see it happening, unless he just has a need as his measurables if recovered/healthy will be solid for a 3-4 LB.
Just my $.02 and it's worth less than that!
Schlante & ROll Tide,
Phillip