Since you're pick #5, I'd definitely go with LT (or whoever drops out of the top 4). I actually had LT as #3 but ended up with Forte at pick 5 since LT was taken right before me.
Here's how I'd rank the four mentioned though:
LT (should definitely improve on last year when he played through a nagging injury and was still the #6 RB)
SJax (very high upside, possibly the most talented RB in the league but terrible team)
DWill (he's just recently overtaken Gore on my board, mainly because of Stewart's lingering achilles injury)
Gore (should be in for a big year as focus of the new offense)
I'm glad to see you didn't include Chris Johnson as an option.
sjax for me, i have a feeling hell be healthy the whole season, and last year he missed 4 games and still managed to have 1000+ yards
14 Team non keeper non ppr espn league
QB P. Manning RB T. Richardson RB Mathews WR Bowe TE Keller Flex D. Martin OP Luck OP A. Johnson DP foote DP ayers D/ST Cardinals K dawson Bench: Britt, Leshoure, skelton, t. smith, mike williams
Desean Williams for one reason..... Durability. He is the only one you mentioned that has been healthy through the last year. Gore and Jax seem like they are always hurt, I will avoid them as much as possible.