Personally, for hunting 200yrds and less, especially varmints and coyotes, I'd go with the 6.5 Grendel or 6.8 SPC. For years, the 6.8 was the better option because ammo and brass were hard to find for the Grendel, but the last few years, this has swapped.

The heavies like the 450B or 458soc are fun, but they drop a LOT. As Ridge mentioned (and I agree), the 458soc generally has the advantage of more good hunting bullets in the market, but the 450B does have the advantage of using cheap pistol bullets for practice - and since you have that 460S&W, you'd be able to share bullets between the two.

The new 22's for the AR are impressive, but when you compete for economy with the 223/5.56, and consider the performance needed for 0-400yrd coyote killing, I just can't find a need for either the Valkyrie or the Nosler in my safe. Just too hard to compete with the availability and affordability of 223/5.56 brass and ammo.

In your shoes, I'd get one well featured lower, then two uppers, one in 223/5.56 the other in 6.5, 6.8, or 450B. My latest two AR's for myself have been this way - multiple uppers for one well featured lower, each. One lower has matching 223/5.56, 204R, and 6.8SPC uppers, and the other lower has matching 223/5.56 and 6.8SPC uppers. I'm currently building a complete 458 Socom rifle as well though, as a complete rifle. Any of them would swap around, of course. I have enough lowers to have fun with friends when I want, so I really don't need to spend extra money on more lowers, just more uppers. A guy is usually better off getting ONE $500 lower than having two $250 mil-spec lowers.

Having watched your range report threads, I'd expect you'd get more mental satisfaction from the 6.5 Grendel or 6.8 SPC than the 450B. You'll see 15-20" drop at 200yrds from the 450B or 458soc, so it's a bit much to manage.

So I'd really recommend one lower with two uppers, one in 5.56/223 and the other in 6.5 Grendel or 6.8SPC, or 450Bush if I can't talk you off of a heavy.