I'm going to throw another out for discussion, because Watkins is the clear favorite ITT already (probably the safest bet):
Lache Seastrunk
EBF pointed out in a very interesting thread about how there hasn't been a 1st round caliber running back the last two years, but I think it focuses slightly too much on the 40 time. Basically saying that Seastrunk looks pretty good, but is a tad slow for someone below 210 pounds. I hear that. But although Seastrunk came in at 201 lbs, his playing weight listed for the past year was at 210. This suggests to me that his playing weight is more likely between 201 and 210, as he probably cut down some for the combine and probably isn't the full 210 listed for his college season.
In comparison, Lesean McCoy measured 210 lbs at the combine, and ran the exact same 40 time as Seastrunk (4.5 flat). Seastrunk blows McCoy out of the water in vertical (29 v. 41) and broad jump (8'11'' vs. 11'). This says that like McCoy, he's fast enough, but no one has ever mistake McCoy for Charles or CJBackWhenHeWas2k. McCoy's game is in his shiftiness and cutting. It looks like Seastrunk can have that same game, but with even more athleticism. Another player who is even smaller, and had basically the same 40 time - Darren Sproles (4.48). He definitely fits the under 210 lbs but not sub-4.4 speed. He's still fast on the field in the NFL.
So the EBF argument against him being 1st round talent basically comes down to 5 lbs and .05 seconds (not just you're argument but the general consensus I think). That's not seeing the full picture - Seastrunk doesn't need the 40 times of Best, Bush, Spiller, Charles or CJ. I think he'll be an incredible weapon at RB with "just" 4.5 speed, based on his other measurables, which are essentially equivalent to CJ running the 4.24 - just not about speed, but more general explosiveness/athleticism.