I'm 50/50 between Ni80 and SS...
I'm not keen on Kanthal because I mainly vape dual coil, low ohms and ramp up time can be an issue. I don't really have a preference between Ni80 and SS. SOME fruit flavours seem better with SS, but I use mechs a lot and I'm not keen on the resistance increasing as the coils heat.
So - Regulated - SS
Mech - Ni80