SW is a little unknown because all the discussions suround DB vs. DT but it is usable on offense now as well from what the numbers tell as opposed to before where it was strictly a defensive move. Do you have other Dragonites already maxed out?
I would say:
Take No. 1 to level 30. Even if you don't like fighting with him you will have a good defender >3k to put high up in gyms. That should leave you with enough candy to evolve another one.
No. 2 and 3 have low IVs and are low lvl. No. 2 is out because of also having SW like No. 1. I think for yor second one you should go for a Dragon quick move. Even though DB/DP is an awesome moveset powering him up all the way would leave you with no candy and cost a lot of dust. Still No. 3 would be a good generalist attacker. It really depens how rare Dratinis are at your place and if you want to wait for another 80 candy and take the risk of getting SW again. (Maybe you prefer SW, idk). Longterm it would be better to wait and if you have enough candy to max out a 90% lvl 20 Dratini, then evolve and hope for Dragon Tail.
