Everyone who asks, "What's your favorite 223Rem load?" is going to get a lot of different answers, like you see. The good thing is that there are many different ways to achieve great accuracy. Or at least something that is better than 4moa XM193.
The first question is that of expectations: is the goal to get clover leafs OR sub moa and close OR "red dot accuracy" 1.5-2.5 moa and calling it good.
If you are just trying to work your way toward smaller groups, one of the easiest things to do is use some inexpensive, yet reasonable quality factory ammo as a way to check your build.
Some like Black Hills, Fiocchi w/Vmax and those are very good. I like Norma Tac 223 55gr. It's inexpensive and if you cant get one, five shot group to be around 1.5", then you know that you need to take a closer look at your rifle.
If you're going down the moa to sub moa to "I want bugholes" road, handloading is the way to go. Generally, a 1:8 should find something good between 55gr and 68gr, but that is not always true. Sometimes another bullet weight is the cat's meow. The thing is, you don't know until you try and no one on a forum can definitively tell you what combination is going to work in your individual rifle. There are generalities, but there are some things that others rave over that didn't work well for me.
If you're loading for volume, ball powder will go faster than extruded.
Also, as the OP noted, getting clean trigger breaks is night and day in terms of confidence.