I have one of White Oak's 16" .223 Wylde barrels on my AR, and I couldn't be happier with its performance. I've gotten 1/2 MOA out of it at 200 yds with 75 gr Hornady match ammo. White Oak's customer service is awesom, too. They're happy to speak with you about available options and about their barrels. I had them flute and bead blast my barrel, then re-polish the outside diameter so the flutes are bead blasted and the rest of the barrel is brushed stainless. Looks awesome, and their pricing for what you get is really respectable.
I'm starting to put together another build from the lower up. I really want a Grendel, but I keep going back to 6.8 spc, just because I can get a White Oak barrel for that cartridge.