The gen 1 su16s are junk avoid them at all costs. They are the ones that cracked, had poor accuarcy due to pos sights.
The gen 2s and 2+ sre rock solid. The pin slots were reinforced... the sites were fixed.
The longevity is unreal for the perceived durability. The nutnfancy project has been rocking one for a few years now. They have over 4000 rounds down range and have beat on it in countless shooting run downs with lots of sustained rapid fire and they are still hitting steel at 400m with it.
That being said.
The vz is by far a better built gun, and you can dress it up however you like. the accuracy is maybe just a little worse,
But it is much heavier.... and you probably want to own a few spare parts (like a firing pin) for it because they are notorious for breaking.
the vz is also a lot less optics friendly. And costs much more.