If you posses any degree of mechanical know-how, my biggest suggestion would be to base it on an action that accepts pre-fits. Especially if you plan to shoot a lot, or use a moderately hot cartridge.
Also, accept the fact that what you like or want will probably change down the road as you shoot more.
It doesn't even really take much mechanical know how. If you can screw a nut into a bolt you can install a shouldered prefit. OP or anyone wondering, it's really that easy. Take out the action screws and take barreled action out of stock/chassis, put the barrel in a barrel vise and tighten the bolts, put action wrench in action and loosen action off barrel, change out barrel in vise to different barrel, then screw on action and torque down and done. That simple. A lot of screwing on and off nuts and bolts.
And being able to do that hits on your second point about things changing down the road. Having a set up like the Bighorn Origin allows you to change as your tastes change. Shooting a .308 but want to try a .223? Change barrel and bolt face and now you have a .223. Same stock, trigger, action and scope so no need to spend a bunch of money on another rifle. Just $450-650 for new barrel and $125 for the bolt face. Want to get a short magnum to hunt with? Same. And then there is changing in the same bolt face so you can have a .308. 6mm Creedmoor, 6.5 Creedmoor and 6GT on the same set up.