Using availability at Midway as a proxy for popularity.
9 loadings from 3 manufacturers. 5 available, 1 you can back-order, 2 coming soon.
20 loadings from 7 manufacturers. 14 available, 3 you can back-order.
.300 AAC Blackout.
45 loadings from 17 manufacturers. 31 available, 7 you can back-order, 1 coming soon.
Grendel and SPC have perked up slightly from last time, I think they've settled into their steady niche.
Blackout is thriving. It remains to be seen if the persistent ka-boom problem of getting the ammo confused will have any effect in the long term on its popularity. Magpul, it should be noted, now makes a dedicated .300 Blk PMAG that's visually and tactilely different from the 5.56 version.