It depends on what you want to do with it.
American Eagle 63gr SP (made by Federal) is my plinking ammo of choice in my ARs. Its cheap, reliable, and reasonably accurate.
Black Hills is probably among the better rounds out there in .223, but it is a little too expensive to plink with. I use it for coyote hunting.
Lake City, ADCOM, and Winchester all in 62gr are my stock pile ammo.
I use Wolf to funtion test new magazines, and guns. It is cheap for high volume shooting. Good stuff for guys that just want to pull the trigger, make noise, and bump fire.