Ok, to clarify things:
Enfield - good quality, some variations due to stage of war production
Springfield - excellent quality
Krag - excellent quality
Swedish Mauser - excellent quality
German Mauser - good quality, some variations due to stage of war production, some could be excellent, some not so much.
These rifles all have good appearance, good fit, good workmanship, etc.
The Nagant was a cheap, easily mass produced rifle that was reliable. Now if you want to call that good quality, that's your call. I don't. In comparison to those listed above, they are junk. I would consider them better in quality than the Ariska and the Carcano's however as those two have a history of extremely poor workmanship and have the odd warning about firing. I've never seen or heard any warning about firing a Nagant or them being in any way dangerous. So if you want a rifle to physically throw into the back seat, pick up at the range and blow watermellons apart, a Nagant for the money is going to be hard to beat. You want something to show off to your grandkids or help fund a retirement off of, it isn't. It will never have the value of a Carcano or Ariska simply because of the numbers produced and surviving to the present day. There are no hidden hoards of either of these likely to suddenly start showing up at dealers like the Nagants are. When it comes to weapons, it's not likely the Soviets/Russians ever got rid of anything. They need cash now, so these old things are showing up all over the place. Supply and demand shows that when there are thousands of something vs hundreds of something else, the less common similar item is the more valuable.
So unless you have in your hands a mint example of an early production run, they aren't very collectible and in all likelyhood, never will be. These will be showing up for years as further stocks are found and released for sale. Not a good investment.