Gyarados time!
One mission of Florida trip accomplished, can evolve my second Gyarados.
Candidate #1 - 98 IV 15/14/15 lvl 20
Candidate #2 - 100 IV lvl 13
27.8k dust and 28 candies to bring #2 to #1. Simple answer #2 right?
Answers
1 and let me explain why. Right now Gyarados doesn't have any awful moves like Twister, but to me Crunch is close. Yes I understand to some it's a great defensive moveset, but defensive moves don't matter for Gyarados it's CP does. A Cp difference from 98 compared to a 100 is incremental. If you evolve #1 and it turns out to be a bad move you can always try again with #2. I'd rather screw up w/ the lower IV Karp than be discouraged w/ the perfect Magikarp.
I would evolve #1, 2% IV difference is just irrelevant, and if this one come best with the best moveset it will save you a good amount of dust, if it doens't you can evolve the #2 later (even if requires a lot of time) and spend the amount of candy that you would spend if evolved #2 in the first place anyway.
Thanks for the input, I'm going with #2, by the 30k dust and 28 candies isn't a huge deal. Know the IV difference isn't big, but by the time I power either of them up I'll be lucky to get another Gyarados within 4 months. I'm currently under a windfall of Carp candies here in Florida, so don't really think the candies will be an issue.