Out of these choiceswhich would you get? And why? If you could only hunt with one of these calibers for everything for the rest of your life

I picked the 300 Ultramag BUT I'm starting to fall in love with my 300 WSM

Way too general of a question.

I like the 300RUM and 7mm RUM because they are very versatile, flat shooting, hard hitting, have great range, and good for just about everything you can take in the CONUS.

I have been shooting a .300WSM for a couple years now. I love it. That gun can do it all. I have taken it elk hunting, come back to the east coast a week later, load a lighter bullet and sight it in and im deer hunting.

Because its fairly hot round, it shoots flat and has alot of power, there are now a lot of different factory loads you can choose from and the ammo is becoming more common to be able to find.

Also, the WSM makes it a small package, meaning when im going up a mountain in Wyoming the size and weight of my rifle isnt going to bog me down. My .300WSM is smaller and lighter then all my friends, 270, 300 win mags, 7mm, 30-06 and so on. I just think its a better all around gun, not to mention this gun can out shoot a lot of other guns, not all , but alot.

However, i will admit that some people dont like the kick on this gun. I am fairly strong and large guy. The kick doesnt effect me at all, but i have some smaller friends that tell me that it kicks bad, i dont notice it so for me its awesome.

Id pick the 270 WSM. I just love the 270 bullets in my 270 winchester. Id love to have a good 270 WSM. Someday i think i will. But a 300 or 325 WSM would be tempting as well. I dont know why the 325 WSM hasnt caught on very well, that 8MM bullet is a dang good one.

I'd have to agree with Griff. Way too general. And being that you didn't list one of the oldies like the 300 oe 338 win mag., my choice would be the 300 WSM.
Reasoning is that it is probably the most versitile of the lot without burning up too much powder and can get the job done for just about anything on this continent without pounding you too badly.

You need to add "none of the above".

DM

There’s no doubt that you can efficiently kill any big game animal with any of the above-mentioned cartridges. I, however, am still in love with the plain old .308 Winchester. I’ve found it extremely accurate in my old Savage model 99, and have dropped an elk dead in its tracks at 200 yards. I am not a fan of extreme long shots, but in my reading, the military has found that is has very consistent drop at long ranges.

None of them.

There might be 2 on the list that won't be completely obsolete/unavailable in 10 years.

IF I had to choose one cartridge for from here out, it would be the 7X57mm Mauser round.........