I've owned all three guns as well as variants, so here are my 2C.
First off, congrats on getting into bolt actions and not just buying an sks right off the bat. While the SKS is the modern every man's gun in Canada, I personally think it isn't an ideal starter gun. It's one I'd probably keep as a beater that would keep on performing the same as it always did, but it's not one that I think is perfect for a new shooter.
Of the Mosin 91/30, M39, and K31, I would choose the K31 for a good all round gun. They are very high quality, great design, and I believe severely undervalued as a milsurp. Yes surplus is more expensive, but it's non-corrosive swiss made match grade ammo.... of course it's going to be. Either buy GP11, or save the money you'd spend on a 480 rd case (good deal at tradex) and buy reloading components so you can reload for most guns. End of the day you'll spend the same amount of money, but with reloading components your investment won't disappear with the last round shot.
I am also a firm fan of the mosin, for a slightly different reason. Only recently they were available for $109 plus shipping... they're very affordable guns that're simple and ultra effective. You don't really hear of them breaking or self destructing ever, which is a big reason they served so long... they simply didn't wear out! They're capable of great accuracy as the guns themselves and the cartridge are well designed. Like anything, inspecting the gun will tell you a lot about what you're getting.
Outside of these, you can also get a K98 converted by the israelis to 308 (phenomenal guns and command lower prices than 8mm k98's), any number of south american mausers chambered for 3006 similar to the K98 (sometimes pretty rough condition, it pays to look), as well as the much overlooked swedish M96 family of mausers in the amazing 6.5x55 cartridge (again, lower prices just because they never saw consistent and publicized front line action). The 6.5x55 cartridge alone is enough to sell me on any manner of gun chambered in it.
So there you go! Hopefully that'll help.