I've got the Tapco adjustable stock on my Yugo. I really like it and don't have any experience with the other two you mentioned so the Tapco would get my vote.
I had to do a tiny bit of work with a dremel tool, little sanding here and there on the stock, but it fit ok in the end. It's not as tight or solid as original wood stock, but it doesn't hurt anything and you can take your rifle back to original config. easily. From what i've heard the Tapco mags are about the best ones going as far as aftermarket goes. I've got 4 of them and they've worked flawlessly so far, although i haven't shot many rds. yet.
I picked up an ATI Collapsible/Folding stock for my Norinco SKS. I am having extreme difficulties getting it assembled correctly. The "just drop it in" approach is not working. It actually has taken wood clamps to get the barrel assembly into the stock. The fitment is so tight that I have the following issues.
1) After I assemble the weapon, I drop the safety (that is bound up)and pull the trigger. It will dry fire once, but it will not reset for a second time. 2) Also the mag cannot be installed after the gun is put togather. So I installed it during normal assembly but, then I cannot remove it. The fix appears to be as follows:
1) The stock needed to have material removed to allow the barrel / trigger assembly to be moved rearward to allow for clearance for the mag to be installed/removed.
2) The stock needed to have material removed from around the trigger assembly to allow for proper function.
But just like anything....YMMV
Every SKS is slightly different, so they're made a bit tight on purpose. Makes it easier for you to modify to your SKS. If it was too loose, it wouldn't work.
If you're considering a full stock like the Monte Carlo, I'd go with the Butler Creek Sporter Stock. It took a little shaving on the inside to get a good fit on my Norinco, but it looks and feels great. Comes with a quality buttpad and costs around $60.00. I'm very happy with the end product!