the benefits that luck has over newton is the intelligence factor and the ability to learn. also there are all those 'intangibles' that make him stand out as a leader on the field. i haven't heard much in the way of newton not being a leader, but luck appears to have it all. luck can also run when he wants and he is not a small guy. sure, newton has a 2 inches on luck and 15 pounds, but luck can handle his own. we aren't talking about some little fragile dude like pike.
i would feel good about either guy, actually, but i feel a whole lot better about luck.
I really haven't heard anything negative about Newton's intelligence or intangibles so I don't know how much better Luck is in that category. As for size Luck is not small or thin for sure but isn't close to being as athletic or as strong as Newton.
With that being said I am not opposed to getting Luck as a draft pick. I am just not feeling that he is the only guy out there or that if we don't pick him we are totally screwed from picking a franchise guy.