What is the mission or requirement driving your ammunition choice?

For military personnel, engaging in combat from 0-300 yards using an M4, the Mk318 Mod0 is the best option readily available via the supply system; the 70 gr Optimized is also very good for those units who can procure it. For folks shooting at 300-600+, the Mk262 Mod1 is clearly the superior choice, along with the 70 gr "browntip" for those commands with access to it.

In a civilian LE or self defense setting, NONE of these are the best options, as the likely shooting parameters and restrictions are far different than in a military setting. My first choice would be one of the barrier blind loads noted in the link I posted above.