Aloha,
IMO as a DD main that owns all three... each plays differently, so depends on what you want to do...
Kidd: Do you wish to troll CV's? Cause thats how you troll CV's. Still has US 127's which IMO are unfortunately power creeped, though they do a wonderful job at starting fires due to ROF.
LoYang: Do you wanna troll capping DD's? Cause thats how you troll capping DD's. The best DD hydro at tier (maybe Z23 gives her a run for her money but still) Unfortunately she has the US 127's too, see above.
Cossack: Do you wanna sneak up on enemy DD's, not be outspotted and have a good single torp fire ability? Cause she has all those things. PLUS with IFHE, she will utterly EAT other DD's, with perhaps the exception of someone in a French DD that is fairly good. Her ROF isn't top notch, but it isn't bad and she hits hard, PLUS, she does have a good % for fire chance, so BB's tend to HATE you.
Just my 2 cents.
Mahalo, Hapa Holidays,
-Hapa