Best ASW is CV or ECL, both with capped sonar (you see sub first), T or R (depends on configuration) with HH or PHH. 1 or 2 gunners (but recomended 2). BO on (E)CL, some light od SS bo (which dont need sailors), ONE eng rest rep tu full slot / displacement.
Armor must 0.2belt bulge to archve cruise speed 34 (you are as fast as submege sub). On CV it depends on you if you put full displacement or not.
On CL is good to have scout with mine to some anoyning mine drop(you cen help BB or scout for your SS or sighting enemy SS).
Fight fire at gradual 1 or 2 at once, see whot sub is doing and fire next time, untill sub deth.
And try to be out of torpedo range.
OH use carefully, on surface ship include surface ss, sonar work only when OH is FULL and NOT USE. Submerged and only submerged sub use sonar all times.
A this time this ASW have range sight advantage against sub.
Good ships US,UK ECL (great nuber R slots), IJN Kita (Nice number T slots). KM Emdem (but there is low usabel space for high leve sailors). MN also ECL. SN Svetlana.
ALL PCV-KM MN,RM have great numbers Rslots. If you use 7 pilots then setup is easy, 1BO(rep or lvl 100 clased 2nd planesman), 2gun,6fighter/bomber,1scout, 1sonar,1eng.
And if you want take some escort as a sonar decoy. (SS thing that you have sonar on it and try to kill it).