Great arguments for several calibers; guess that's why they make so many. I currently have centerfire rifles in 15 different calibers - my two favorites are .30-30 and .22-250. If I just get one it will be the .22-250.
300 win mag and 338 win mag, I love the kick of a good mag rifle, but the browning a-bolt in 338 is a dream to shoot they know how to make a quality rifle super accurate!
Just got a .22-243 finished--hope it lives up to expectations
7mm-08--long range, minimal recoil in a Rem 700 short action
338-06--available in commercially loaded ammo if one can afford it, but easy conversion of '06 brass
These are three of my favorites. I also like the 25-06, 22-250, .243, 6.5x55, .375 H&H Mag, .223 . . .
Though I have some 30-06 rifles, they are not my favorites. The only .270 I own is a Savage 110 I bought for the action with the intent of putting a different barrel on it. But, looking at my array of calibers, I haven't been able to find anything that adds significant capability to what I already have, so I may just sell it.