Love this topic. For me, there's lots of "ifs, buts, & maybes ...", so here's my list/s:

What i really like:
17HMR
20cal wildcat (eg; 204 reamed chamber to 223 length)
300WSM ('cause I've got one & love it - can be loaded from mild 308 to near 300WinMag)
9.3x74R double
450 x 3 1/4" double

If practicality is an issue (ie ammo availability, legalities, etc):
22LR high quality bolt, or a Ruger 10/22
223Rem bolt (or, if necessary substitute 222Rem or 22-250)
308Win or 30-06 bolt or single (if necessary, substitute 270Win)
375H&H bolt
470NE double

This list, of course, completely discounts bird guns. One simply must have a bird gun (for me a high quality SxS game gun in 20 or 12 bore - maybe even 28), & a well fitted O/U 12 bore clays gun.

I could live the rest of my days in bliss if I could travel the world & each year have cause to use all the arms in one or the other list (& the shotguns).

Not greedy at all, am I?!