Straight line speed?? Vick maybe, but only slightly IMO.
IMO Vick has better initial explosion and quickness, but I suspect RG3 has better long speed than Vick.
Vick's longest TD run in the pros is either 53 or 58 yards, depending on what source you have. I'm not sure which game that was.
Everyone knows about RG3's 76 yd TD run against the Vikes.
Elusiveness?? Vick. Like many others I believe Vick could have been a pro bowl RB in the NFL if he switched positions.
But RG3 is more than a north/south runner.
Raw athleticism for a QB is a double edged sword.
Being the best athlete to ever play QB in the NFL made Vick dynamic and exciting, but it never made him a dominant
Speed and quickness should be used by a QB IMO to compliment his overall game, it can't be the foundation of what he does on the football field.
We can all imagine if the football gods suddenly gave Brady 4.3 speed. I doubt Brady would decide to start running for a 1000 yards a season. Brady would probably become unsackable,the Pats would probably have a 90% conversion rate on downs of 5 yards or less and Brady's play action would be mind numbingly indefensible.
I believe guys like Brady and Peyton would be very judicious in how they used their athleticism if they were elite athletes, since one of the goals of any QB should be to not get hit.
Vick in his prime, GAOAT(greatest athlete of all time) to play QB.
RG3 is the fastest currently playing.
And because I rate size/strength as an athletic attribute, Kaepernick and Newton are probably the best overall athletes playing QB today in the NFL.
RG3/CK/Newton are all significantly bigger than Vick, so I think their value to an offense long term is higher.