I have a Logitech g502, so I have 2 extra buttons next to m1 and 3 on the side. Quick melee is always on a side button as well lol. Holding middle mouse to aim grenades always feels awkward to me because of the roll, and that’s always been my first switch to fail on pretty much every mouse I’ve ever owned. I honestly think it’s the single worst physical key to bind an action to in a video game from a tactile perspective.

In super fast paced fps shooters I usually use G, but that’s just because of muscle memory going back to like Half-Life 1/CS1.6. I tried swapping to a side button for my grenades in the finals and it was not viable for me at all lol.