When throwing punches, should I be exhaling through my mouth or nose? From what I've seen it looks like a matter of preference for most people, though it seems much more comfortable for me to exhale through my nose.
But I wanted to make sure I start without picking up bad habits so thought to get some advice on here.
Thanks
I breath in and out through both my mouth and nose in whatever sport i'm doing. It doesn't make much of a difference.
You exhale during the energy consuming part of action, so i would think most boxers exhale while letting a punch go. 
Exhale through the mouth.
Definitely mouth. You can push harder with your diaphragm when exhaling through your mouth as well as have more power in your strikes.
Besides if you mess around and blow to hard out your nose you're gonna get snot everywhere haha.
As a follow up, i've always found the debate about mouth vs nose very strange. They both lead to your lungs, and the air you are breathing in is the same. The only difference is that you can get less air in and out through your nose at any one time, so unless there is a specific reason for having your lips shut, i would always say breath out of both.
"Breathe through your nose, breathe through your mouth, suck air in through your ears if you can!" - some marathon runner