They are very addictive. As many members have stated, one of these rifles is often not enough. I have to admit, that I am guilty of owning an over flowing crate of each (SVT, Mosin and SKS).
My first was a Chinese SKS-D, purchased on my behalf by my father when I was only 16 or 17. Heck, the only cost about $40 more with the Lever Arms Christmas sale and that was over a decade ago. Heck even 7.62x39 is about the same price, maybe $20 more.
Then I got into milsups with the purchase of an RC K98 about 8 years ago - ever since I have been in deep.
Pure dollars and sense - probably the SKS. You can now hunt big game with that calibre in many provinces; its semi auto; ammo is cheap; and those that fear guns like to think of it as an 'assault rifle'.
I think it would also be easier to find ammunition, especially soft tipped ammo when compared to the 7.62x54r.
From the historical stand point, probably a Mosin or SVT. Both have significant history and were used in WWII (the Mosin also used in WWI and in multiple post WWII conflicts). Heck if its good enough to kill a Nazi, its good enough to shoot tin cans.
If a guy could manage, I would recommend all three, especially the SVT and SKS with the Lever Arms Christmas Sale. No...I don't work for Lever Arms, but that sale is unbelievable and you will be hard pressed to pick up one of those rifles for any cheaper...period!!! Heck, you can pick up both, for less than what SVT's were selling for only two years ago and you could pick up a Mosin for less than an SVT sold for six years ago.
SKS's extremely reliable. As long as you clean it, it will not fail.
Mosins are crude and simple.
SVT's are finicky (due to the gas system/ammo) but a pretty interesting rifle/design.
My two cents.
P