Hexmags work just fine, but I find the polymer they are made from a little 'slicker' than the textured finish of the PMAG. Not a big deal unless they get covered in something slippery, we did a drill where the instructor covered our hands in baby oil (sounds weird but a useful experience) before we ran through all of our usual reload / failure simulation drills, and I was glad I had PMAGs with me instead of Hexmag / USGI.

For general range use, Hexmag / Troy / MFT / USGI are all fine IMO. They're probably all fine for any purpose but I stick with PMAGs and USGI because it's what I know and the cost different is so minimal.

(Side note: I have read of people having problems with the over-insertion stop on the Gen M3 PMAGs but haven't experienced that myself)