Smith, easy
The age is no factor. Just a few months difference. Both are extremely young.
Smith is taller, more agile, better runner, more variety of loft and pace, less mechanical, probably smarter, and was a higher rated prospect coming out of high school.
As I've posted before, that's extremely important to me, pedigree and early evaluation. No chance I'm falling for someone who was a marginal prospect at Butte Junior College just a couple of years ago. The guys who go broke in Las Vegas pull crap like that. They see some team lose a basketball game to Duke by "only 7", then decide to give 6 points with that team the next time out. Guess what, they lose by 7 again because they're not that damn good. I realize that doesn't seem like a relevant comparison, but what I'm trying to emphasize is you need to rely on a long history of excellence if you're making this type of investment, a QB at #2. Smith isn't ideal in that regard, either, but he excelled in a good league in the San Diego area and, IMO, is much less likely to bust than Aaron Rodgers.