I also have a quirky desire to own guns chambered for slightly less common rounds. My 870 is a 20 gauge (not uncommon, but LESS common). My first rifle was a 17 HMR instead of a 22. But I'd have to say that it would be very difficult to find a better rifle for a beginning hunter than a 243. It is a perfectly adequate deer cartridge in every way. It carries more energy than needed for any deer out to 300 yards, and nowadays its easy to choose a bullet that will hold solid and penetrate even on shoulder hits at the high velocities of close range. The great thing about getting a 243 for this hunter would be that they could also use the gun for things like coyotes, woodchucks, ground squirrels, etc. They wouldn't need a new rifle just to hunt a new location where long shots could be encountered.
But, with all that said, 243 isn't the only good option. 260 rem, 6.5x55, 6.5 grendel in an AR, 6mm, or the lovable 257 Roberts would all be more unique and interesting cartridges without being rare or obscure. All of them have good factory loadings available and likely will for the foreseeable future. All have very low recoil and shoot flat and accurate. I'm out west, and so perhaps thats why I would choose cartridges like these.
Bottom line, get something that tickles your fancy now, and won't hinder this person from pursuing a variety of hunting opportunities down the road. Thats why I'd choose 243, because of its greater versatility for varmints as well as deer. Generally most new hunters wont be pursuing moose in saskatchewan within the next few seasons, however varmints are always on the menu and a great way to hunt year round.
