If all of the rifles mentioned are in their "as issued" condition, my choice would be the Swede, assuming suitable ammunition is available. Let me say that I have no experience with the Swiss K31 rifle, so I do not include it amongst my considerations since I have no basis of comparison with it. The Swede is light and well balanced for a military rifle, recoil is lighter than either an 8X57 k98 or a 7.62X54R Mosin Nagant, and accuracy has been very good in most of the examples I've owned and used. The #### on close action is a small advantage in that partially withdrawing the fired brass and cocking the action do not occur simultaneously, so running the action requires less force. Arguably the Swede and the Mauser are likely to have the better triggers than the Soviet rifles, which does not relate to inherent accuracy, but to the ease by which one can apply inherent accuracy, quickly and effectively. In other words, the better the trigger, the easier it is to shoot the rifle well in practical applications like hunting.
I don't particularly like the Mauser style rear sight, but its not impossible to mount a receiver sight or an optic . . . if you're not opposed to drilling holes in you rifle's receiver, there is the option of mounting a receiver sight or a scope. Drilling and tapping the receiver and then mounting an appropriate scope can probably be done is less time than drilling and tapping the receiver for a aperture sight, then figuring out how high a corresponding front needs to be, and then attempting to acquire one. By contrast, mounting a scope, and bore-sighting the rifle normally only takes a few minutes. If you intend to use the issue sights and keep your rifles in unaltered condition, it might be worth painting the face of front sight with a contrasting color so it stands out against both the target and the narrow notch of the rear sight.
The real answer is that you probably already know which rifle to use. Its the rifle you like the best, snap shoot the best, and find the easiest to carry. All provide suitable energy to have the expectation of killing a deer quickly with a well placed single shot, so power is not a consideration. An inch difference in group size from slow fire prone, or worse, off the bench, at 100 yards target is irrelevant to hunting. A 3 inch difference in trajectory at 300 yards is likewise irrelevant. Even if there was an opportunity to take a 300 yard shot with a scoped rifle, the target is large enough to be within the margin of error, but its unlikely you would even attempt that shot with the issue sights on the rifle, and almost as unlikely if you had a receiver mounted aperture sight, if the light was poor. If hunting in thick cover, where ranges are typically within 50 yards, and almost certainly always within 150, a fast handling SKS comes into its own with its ability to provide a rapid follow-up shot.
