Probably my Savage 111FCNS 7rem I have right now...not fancy but shoots absolutely lights out and I have 110% confidence with it. My close 2nd would be my Brown Custom 7Rem (built in 80s and sort of handed down from my dad) again a lights out shooter its super light but it does punch a little more than the Savage.
Probably a 30-06. Very wide range of loads available. Readily available range of factory ammo and reloading supplies. Enough power for anything in North America without providing way too much gun for lighter game.
I only have one hunting rifle (not counting the 22). The Tikka .270 has done everything I have wanted with a 130 grain Barnes copper bullet. Sometimes I daydream of a bigger caliber, but with most of my hunting days behind a bow, I can’t justify it.
Rem 700 in 30-06 parts are everywhere ammo is everywhere. Reliable. many configuration and has the knock down to kill anything pretty effectively on this continent.
I built my “one big game rifle” in 300win mag, I’m rebarreling now to 300 PRC. I have spare barrels for it in 416 Ruger and 458 win mag. My wife has a matching rifle with barrels in 7mm Rem mag, 338 win mag, and 416 Ruger.