I've given you the powders; I'm sure you would rather work up your own loads for your guns than use mine.
What I will tell you is that AR Comp is a re-formulated version of RL-15 to make it more temp stable & during that conversion the burn rate has turned out to be a tad faster; powder granules are also smaller & darker.
In the order of flowability (through a Redding 3BR), MR-2000 is the finest powder from a grain size & flows the best, followed by 8208 & then AR Comp; all flow better than RL-15 or Varget & all fill the case to a lower level as well. All 3, on my scale, don't vary more than a 1/10th of a grain.
RL-15 is fine & a very good powder, & I use it in several bolt guns; Varget is very good & I use it occasionally in a 7-08 with certain bullets, but in a 5.56 case, it's just too bulky, especially with 77 grain bullets.
Do your testing & make up your own mind.
MM
