I've been using either Benchmark or Varget I have picked up a can of Reloader 15 to try and get away from the lot variance of the Varget. If I cannot get good results I will just buy my Varget in larger quanities.
Benchmark works great for 60 grn and under in my 18" and 16" 1-9 tubes. I use the Varget for the 69 grn and also use a lot of it for .308.
Ramshot TAC or XTerminator are really cheap and work great. XTerminator is best for lighter bullets. Both are spherical and meter great.
Also have used IMR 4895, Reloader 15, Varget. All have given good accuracy when I've tried them.
I started off with IMR4198 but it didn’t meter too well so I tried Winchester 748 and I’ve been pretty pleased with not only the way it meters but with the good performance as well.
I do and have used most of the usual suspects all with good results, but I often buy H335, TAC and 4195.... I use 4895 for .308 and it worked well for .223 also. So, that is what I have been stocking up on lately, I think its good to have 1 go to powder for both calibers.
All the powders previously mentioned are good powders for the 223. The line of powders I didn't see mentioned is the VithaVouri line of powders. I use VV N133 with 40 to 50 gr. bullets. VV N135 with the 55's, the previously mentioned Win. 748 with the 60's, and VV N540 with the 69's and heavier. If I could only have one powder for the 223 it would be VV N133. FWIW, if you have a 6 PPC, N133 is a great powder for it as well.