in general the major 3 choices are sbx/cmss3d, dolby headphone and razer surround and generally in that order although that may shift due to your preferences.
given that the m50 has a very small soundstage you might be better with dolby headphone as it sounds the furthest away although sbx would likely work too. i'd likely avoid razer as it sounds closer although of course if you need free it will certainly work.
any will work, what works best depends on preference. the m50 itself isnt really ideal for gaming due to its small soundstage but it can certainly work.