Ask yourself are you going to hunt deer with ,or bigger game.
I shot my deer with 25/45 this year so that's what I have been playing with.I have played with 300blk,and still have it,just always end going back to 25/45.
But other calibers if I wanted to build one today would be.
6/45. -lots of bullet choices if you do reload
6.5 grendal. -better for long range,but cost more different bolt and mag.
277 wolverine. - This is a new caliber,i think it is similar to 300blk ,but a 270 caliber bullet ,better than 300 blk.
300 blk is ok ,lots of bullet choices but is a 200 yard tool at best.