Depends what you're after. All were more than likely used in WWII but only a few years were produced in WWII. Appearance, any prewar is going to have a nicer finish to the metal work. The stocks will most likely be about the same condition although some have a better fit around the rear of the receiver than others.
Tula is generally preferred because it was the primary arsenal of the Soviets and is felt by some that the product produced is of a better grade. WWII production Tulas are much less common as the factory was overrun by the Germans and the equipment moved east. Pre-war Tula's are more common than Ishevsk.
A WWII production rifle with a smooth finish may be an ex-sniper. These were in general finished to a better degree, can tell the difference by examining he interior of the receiver and looking for screw ends showing where they were inserted into the holes and then ground down prior to refinishing.
Ex-sniper, hex receiver and laminated stocks all get a slight premium over others. Bayonets should have matching numbers to the rifle but rarely do because the seller doesn't take the time to look at them before shipping, you can ask him to check. They are shipped with the rifles but loose in the crate and they usually just grab one without checking numbers.
Handguards with brass fittings look sharp compared to those with black steel. Stock dog collar holes come in several varieties, no metal insert, partial metal insert, full metal guide and full metal guide held by screws. The ones with the screws are the oldest, the full metal guides are generally on better finished stocks.
Four numbers on the rifle should match, bolt, butt plate, receiver and magazine base plate. Bayonet as well as noted above but not often considered as necessary. Some will be force matched with a previous number lined out and the new one next to it. These would be less desirable.
For function, all will work about the same, all are very efficient, it is a simple design and they are nearly indestructible. For appearance, the earlier the better. I have never seen a re-arsenaled 91/30 with a bad bore but some are better than others, hard to get that off a photo though.