Since NASM/YASM is written in C, it's more portable. On my ARM Mac, NASM works fine.

FASM is cool (and still being development), but since it's written in 32-bit x86 asm, let's just say macOS is a 2nd class citizen.

I prefer FASM but NASM is a strong second choice. But at the end of the day it really doesn't matter.. purely preference.

fasm absolutely rules on windows