The early model PS1s and PS2s were kinda cheaply made to keep costs down since Sony was already losing money on each unit sold. I seriously wouldn't touch a used model unless it was next to nothing to buy. The slim models of the PS1 and PS2 on the otherhand seem to be much more durable and probably have much less wear and tear since they came out at the end of the lifespans.
Nintendo was also smart in limiting 3rd party developers to only 5 games per year. While some crap did get through (hello LJN) for the most part it did keep the marketplace from being flooded.
Nintendo and Sega had enough talented developers in-house to where they could support a system pretty much by themselves and Nintendo had most of the top tier 3rd party developers working on the NES like Konami and Capcom. Atari neither had enough top tier developers in-house in the late 80s nor did they have much in 3rd party support (largely due to Nintendo locking in 3rd party developers).
I bought an Atari 2600 in the late 80s because the console was only $50 vs $200 for the NES and the games I bought were $1-10 clearance games for the most part. It was all I could afford being a kid who got $10/week for allowance plus birthday/Christmas money and whatever money I could get from recycling cans and mowing lawns and I had to split that money between video games, sports cards, GI Joe, and Transformers.