Well, in the “Rifle Country” context, I would say that my “most versatile” would be my left-hand-action Winchester Model 70, .375 H&H, at least on paper. The problem is that I never became a global-traveling hunter. A feral hog is the largest animal I am ever likely to need to shoot, and they do grow quite large, here in SE Texas, but I do not “hunt” them, so, the scenario would be pest control, or, perhaps defense. (A women was killed, a few years ago, by one or more feral hogs, in a residential driveway, one county to our east.) Feral dogs, or feral humans, would be a more-likely threat. On a practical level, .357 Magnum is the versatile cartridge that I need, so the “versatile gun” can be revolver, with some heft, and a barrel length that allows some work to be done, at more than just close range. I have several 4“ to 6” Ruger .357 revolvers that meet that description, including the 4” example, a GP100, in my avatar photo. It served as my duty handgun, for a while. Practical, and versatile.
I have a lever-action rifle that chambers .357 Magnum, a Browning B-92, if the answer has to be given in rifle format. Notably, THR member chicharrones, a fellow Texan, chose his stainless steel .357 Marlin lever rifle, as his answer to this topic’s question. A stainless finish is a good thing, in this humid coastal SE Texas climate, so his Marlin bests my Browning, in that regard.
My avatar photo was snapped, with an iPhone, among thick vegetation, so as not to be visible to anyone, who might be alarmed, but it makes the point that a handgun can be the “most versatile gun,” depending upon one’s locality/environment. (On another forum, the topic of gripping a revolver, including hand, finger, and thumb position, was being discussed, which is why I snapped a series of images, with GP100 in-hand, with my finger on the trigger. The Rules were being properly observed.)