For me, it's always Xeno, mostly because of its taper and that shorter length. KeyMo, sure it's built like a tank but honestly, it just adds extra weight that I simply don't need to be carrying around.
I always seem to gravitate back to Xeno. I just really like how simple it is and how light it keeps things. KeyMo feels incredibly solid, like a tank but you notice the extra weight once the suppressor is on. ASR is perfectly fine, I guess but for some reason, I've never really felt a strong sense of trust in it.