So my brother and I started hunting coyote calling contests in Oklahoma about seven years ago. We did alright on the first few then we started noticing the number of coyotes we were losing, with v-max, accutip, JHP, it didn't seem to matter. Losing three in one contest, costing us about $1,500, was the last straw so we started looking for more. Our hunting partner uses a .243 which I think is [beeep] but not in the ar-15 platform.
Then we stumbled upon the 6.8 SPC. He went ARP, I went Bison. Now five years later with well over 100 killed and I can count the number of coyotes we've lost on three toes. There really isn't a better round in the AR-15 platform for the distance that we hunt.
I've used Hornady 110gr V-max, S&B 110gr PTS, SSA/Barnes 95gr TTSX, SSA/Barnes 85gr and 110gr TSX, and even Nosler 110gr Accubond. Really they all performed except a couple of the TSX's that didn't open up, but they still killed the coyote. Now I've been loading Cavity Back Bullets 105gr MKZ to about 2750fps from a 16" barrel. They have been performing great with 15 coyote kills between me and my brother and one bobcat. They just flat out work.
Since I've gotten more into reloading I've looked at the other offerings: 6.5G, 300BLK, 6x6.8, 22x6.8, 224 Valk, 22 Nosler, etc. For me, the 6.8 SPC does it well enough that I really don't need to look any further. No the speed isn't up there with .223, .204, or .22-250. But the energy beats them all except the Grendel. And that's fine. With the Grendels early feeding issues, lack of performance from shorter barrels (which I prefer for the type of hunting we do) and, from what I've seen, the lack of available factory ammo, I still think the 6.8 SPC wins out. Now if you're in wide open country and want to shoot coyotes at 500+, Grendel I guess. And I'm not against that. It's all about using the right tool for the job. A .22LR with iron sights isn't good for 800 yard shots and a .308 with a 24x optic isn't good for 25 yard creek hunting.
I don't know if I'm a bigger Trijicon, 6.8 SPC, or Knights Armament fanboy.