Federal Premium is hard to beat, though the price has reflected that the last few years. I like Hornady products, but i don't shoot enough to have any real useful opinions here.

As for modern ammunition has greatly improved in the last twenty years.

One cannot say what is the best for your gun. Take WA Mtnhunter doesn't like Hornady, but I've won a many High Power Matches with that brand while Sierra loads don't come close starting at the 300 to 600 and especially on the 1000 yard line.

What shoots best in my rifle may not work as well in yours as the other way around is true also!

Type and grade of barrel, Barrel twist, barrel whip and muzzle crowning to name a few all have a major impact on the performance of your load. Crowning alone makes a difference on the accuracy of spitzer and boat tail bullets.

In my rifle Federal Fusion and Remington Core Lokt work well. Win Super X are all ove rthe target. It is a matter of what your rifle likes though.

I would like to clarify my statement about Hornady ammo. I had success with it in the past, but three of my buds have had the same issues lately. I still handload Hornady bullets and will probably continue. I won't be buying anymore factory ammo from them or Interbond bullets. I am waiting to see what Hornady does with the ammo I returned for testing. I really don't want replacement ammo of the same kind unless something has been identified as the cause and corrected. I guess that I can always use the brass!

Whatever you get the tightest groups from (every firearm is unique), combined with what you're willing to pay. The artwork on the box is about all that's left after that.

Hornady, Remington and Winchester.

What is the best factory ammo? The answer is simple: Whatever your rifle shoots the best. My .270 likes Remington Core-Lokt Ultra, my 7 mag likes Remington Primium in Swift A-frame, etc. You have to shoot several to find out what your rifle prefers, then stock up on it or start reloading and work up a load for your rifle.