My go-to powder for .223 in AR-15 is H335 and 55gr bullets
My second choice is CFE223, because my reloads with this powder nearly duplicate the H335 load, thus I don't have to make any adjustments to the sights. The CFE223 loads did chrono a little slower though, at least out of my 16 inch barrel (1:9 twist rate if that makes any difference).
I'm attaching some photos taken from a range trip this weekend where I did a side-by-side comparison of the two loads.
Test rifle was a Windham Weaponry AR-15, 16 inch barrel, carbine length gas system, 1:9 inch twist, iron sights, from a bench with a really crappy rest. Test shooter, myself, is less than perfect, had a few "flyers" in my groups that I think were just me goofing up not the gun or the ammo. Ammo was loaded with mixed brass (some Lake city, some commercial), with "bulk" Hornady 55gr soft point bullets, and powder chargers were not individually weighed, they were just tossed from a cheap Lee "perfect" powder measure. Basically this ammo is the cheapest and fastest to produce, NOT match grade stuff. Primers were CCI 41, the "mil spec" primers that come in those white boxes. All groups fired were 5 rounds.
Test #1 was to shoot at paper plates at 100 yards and compare group sizes. I get the plates at the dollar store, I like them because they're cheap and easy to see with my bad eyesight (I'm not that old, 34, but am very near-sighted). Had 3 "flyers" out of the 5 shots with the H335, and only 1 flyer with the CFE223. The 3 good H335 shots in the group were very tight and I was very pleased, especially considering the cheap/easy nature of the ammo. The CFE223 group was larger but POA/POI was pretty much the same, so I was still happy with it. See attached photos
Test #2: Had my Dad shoot 10 rounds of just the CFE223 load at 50 yards. Attached photo with the orange/green target (there were 3 holes in the paper already, we used a recycled target, pre-exisiting holes were circled with a black ink pen). Dad is probably a better shot than me but he normally shoots with optics not irons.
Test #3: Shoot each load at 175 yards at IDPA style silhouette target. See attached photo, I color-coded it so you could see where the rounds hit. Again the H335 loads made a tighter group (aside from the 1 flyer). The colored holes are mine, the unmarked ones are rounds my Dad shot, again only using the CFE223 load, and again he shot 10 rounds.
So yeah, conclusion: both loads are minute-of-zombie out to 175 yards, don't need to adjust sights, but H335 gives me better groups. Your mileage may vary. Hope this helps...