What is your thoughts on a good 30 cal magnum? 300Win mag or would you have you gone/go a different caliber?
Any of them that are of a platform you can carry far AND shoot well. I've owned a 300Winmag of some manner since '97. I also owned a 300WSM for ~10yrs. There's not enough difference ballistically to firmly make a case for one or the other. Belts on cases don't bother me as I minimally size my brass and headspace off the shoulder anyway so again, no clear advantage. The "traditional" longer cased 30 magnums like the 300Win, 308 Norma, 300Wby, and 300 H&H do have an advantage in very smooth/slick feeding and the 1st 2 are typically are housed in a platform that allows a handloader more freedom regarding seating depth, especially with heavy (180gn+) bullets.
All that said, none of those differences make much difference. Find the rifle YOU like, then find the ammo IT likes then just go fill tags. 3 of the 9 elk I've killed, I was damned glad to have the 300. 2 due to poor 1st shot placement, 1 due to a pretty hard going away angle that required lots of oomph to get where it needed to be. The other 6 could've been killed with anything a guy would normally pack for any deer or antelope hunt. The moose I shot would've died just as dead and just as fast with any non-magnum '06 or 308 based round, lets face it, broadside standing still and calm @ 200yds with vitals the size of a large beach ball offers a guy lots of margin for error. The 2 caribou I killed with a 270Win left me well satisfied that a guy certainly doesn't need any more gun than that as neither took so much as a step post-impact.
1. Placement, placement, placement, get the bullet into the vitals
2. Bullet, pick a good one that shoots well in your rifle, then shoot it enough to
KNOW where it's going.
3. Range, knowing exact range, is much more important that the headstamp upon your ammo because it's a much more important part of putting the bullet in the right spot than is case capacity.
4. Wind, knowing how fast the wind is, what angle it's at compared to your intended target, and having a well thought out and repeatable method for accounting for that wind is again far more important than the headstamp upon your brass.
There's probably a dozen other things I'd worry about before worrying about which specific chambering to buy. Scope, mounts, stock to metal fit (bedding), good trigger break, all mean more to me than does a specific chambering.