Ok wait... I'm assuming that what you mean is something more like, "If a thief were to take all of your rifles today, what rifle would be the first you'd go after when you got the insurance check?" rather than "If you were a new hunter today, which cartridge would you look at for your first certerfire rifle?"
The answer to the lformer question would be 30'06. The answer to the latter might be something more tame like the 30-30 that I really did start out with (those were my first two centerfire rifles... the old WCF and the '06) or perhaps a 7x57 or 7'08.
If the question were something more like "Of all the cartridges listed here, which interests you most as a hunting cartridge?" I'd answer 6.5-284 Norma, followed by the 338 Edge as a hunting round... (rather than a shooting round) ...a long range hunting round... the Edge would be da bomb for sure. But for an all around fun rifle to own I'd go for the Norma cuz I'd be able to shoot the heck out of it.
In truth my next completed rifle will be a 338'06 A-Square, followed by a 7x57, 9.3x62, (these three are in the works) 6.5-280 AI (I have an action set aside for this one), followed likely by a 6mm-223 Rem, and then perhaps a 270-308 Ackley Imp.