The 30-06 and just about everything based off its case are both classic and effective.

My 280 was outstanding in Africa this year. Zebra, Kudu and Impala all one shot kills at 200-230 yards. Couldn't ask for anything more.

I vote for the classic .308 cartridge. Anything that came from Uncle Sam is good enough for me too! I love my old Savage .308 with the Bushnell Trophy 3-9x40 scope. Common setup, do anything, go anywhere, etc... I have it sighted in 1" high at 100 yards and it's always dead on with tack driving capability, if I do my part too.

Use what works or what is entertaining at the moment. It is boredom that has provided my gun collection. 30-30, 32 win spc, 308, 30-06, 338-06, 7-08, 7rem mag, 280 rem, 300 win mag, 300 win st mag, 348 win. No longer have 35 rem or 35 Whelen, just get bored with an action or caliber. Some of these sizes have duplicates calibers in different platforms.

Interested in a 25-06 or equivelant, also have interest in some rimfire rounds for Florida small game season wma hogs (some have lots of restrictions).

Got to change it up and keep it interesting!

I once had a 32 Win. Great little gun. At the time ammo was kind of hard to find and so was loading components. I traded it against a Ruger 77 in 243 on a day when I wasn't thinking right. Wish I still had the 32 since I later traded away the 243. Hind sight don't ya know.

While many of the "newer" cartridges I think are only trying to re-invent the wheel, I certainly understand the need/ purpose of the new cartridges aimed for the AR platform.
That said, I am not into the semi - auto form, so my closet is very "classic".
The well proven 45-70, (but actually reinvented with modern jacketed bullets and modern powder)
30-30 (again, powders and bullet construction take its performance up a long ways)
8 x 57 Mauser - not so often found today, but my favorite, and needing a close look by any one looking for a new round,
.308.
No need for nuthin more here.