It all comes down to one thing putting a hole in the vitals. Pick the weapon that you trust your ability with first not what has the most punch. Do you need a big mag no you can get the job done with less. Is the extra power nice if things go side ways yes

smaller caliber rifles, bows, and black powder have taken grizz without issue. They can get the job done just fine

Big mag hits harder but you still need to put the shot in the right spot

For myself and many others our accuracy with the big mags is not the same. We have all seen the super hero at the range with the big mag who can't keep a good group. Also seen guys who keep tight groups

Guy has to choose what fits him best big mag or lighter caliber depends on the shooter

Lots of choices out there that will work fine for grizz been in on 30 06 kills and know of those who used a 270(getting light here). Heard of things going sideways with both lighter caliber and big mags neither caliber failed the shooter did