Each caliber/chambering has its purpose, benefits, and cons.
For me, the 6.5 Grendel encompasses more benefits and less cons than the other when looking at performance alone.
From a 10.5", 11", 12" etc. Grendel, you have more energy at the muzzle than a 20" 5.56 NATO, and it only gets better from thereon out.
My 12" Grendel has more energy at 400yds, than a 24" .30-30 Winchester has at 200yds.
The SBR Grendels will exceed a 16.3" AK b 50yds, then maintain supersonic speed and effective range much farther, shooting the exact same 123gr weight from the same basic case.
You can take medium game on the heavier side with authority within 250yds shooting the 123gr SST factory round.
129gr Nosler Accubond Long Range has already been used multiple times to DRT deer and hogs from 11" and 12" barrels.
I have already taken my 12" out to 800yds with 123gr Hornady American Gunner (139.95/200rds at Sportsman's Warehouse) and couldn't believe how easy it was to hit over 90% hit rate, with an unknown zero on the scope, just using the GRSC reticle on a 1-4x.
Cons with 6.5 Grendel:
You lose 5 rounds from the mag in comparison to 5.56 and 300 Whisper.
No Magpul PMAGs
You'll want to convert more of your ARs over to Grendel