I also love the 250 Savage, so classy, so good.
I already have everything to load 250 Savage, including a lot of brass, and bullets.
Don't make this complicated. The .250-3000 is easy to load for and you already have everything. It's going to be more efficient than any of the other choices discussed and better suited to your proposed 20-inch barrel length. (A 20-inch .25-.284? Think 20-inch .25-06.)
The only other choice I'd consider would be a .257 Roberts.