I think 99cruiser is giving you great advice: 1. Records, 2. Damage, 3. Undercarriage/Rust.
(In no particular order)
If all other things are equal (ie no interior/exterior color preference), I’d go with the one that has best tires/brakes/hydraulic fluid changes (think AHC, gear boxes, diffs).
If things are still equal beyond that I would personally go for the 2014. 15k miles would make no difference to me whatsoever. I’d rather have the slightly newer car (keep in mind that, IIRC, there will prob only be a 6 month production diffence between them as 2013’s were usually built “late” and the 2014’s were built early.)