The Nosler 69gr HPBT over Varget, Reloder 15 or H4895 works well. (Yes, I've tried that bullet with all three powders, plus W748. Don't bother with 748 for bullets over 60gr, very temperature sensitive when running much over mid-level loads. It's fine with the 52 and 55gr bullets though.)
Also good is the 77gr Nosler HPBT. I haven't tried the 68 or 75gr Hornady's, but they have a large following and shoot well. And you can't forget Sierra's Matchkings either.
The one bullet I want to try when I have a non-competition .223 is the 64gr Winchester Power Point. It's marketed as a medium-game level bullet (it would be 100% legal to use hunting whitetail here in NH). And again you can't forget Sierra, who makes a 65gr Gameking that should have the famous Sierra accuracy.
Oh, and I know a number of shooters using the 75gr PRVI bullets W.E.G. posted the link for. They shoot well also, though a couple of the users seem to question their (the bullets) accuracy at 300 yards from time to time.
Does that help get you started?
For powders, stick with your Varget, Reloder 15 and H4895. I'm on the fence between Varget and RL-15. Varget burns cleaner for me and is an emotional favorite because I've been using it so long, but RL-15 will do everything Varget will do in .223. H4895 works well at a couple of grains less charge weight as another option.