The other ax rads are full price, imo not worth it. Better to fill up on cheaper good radiators than to spend double on ones which only perform a degree or two better.
Do you know how much space the case has for radiators?
Everywhere i search seems to give a different answer and the NZXT website only says a dual radiator but surely not with a case of this size.
I recommend saving cash ad grabbing the EK PE radiators over the black AX ones, as they are practically the same but half the price.