The NES isn't bad as long as the pin connector is cleaned properly, I have a good quality 3rd party cleaning kit that works great. I did have a system that had a graphics encoder chip die on me, at least all the graphics got screwed up no matter what game I played and no matter how much I cleaned the system the problem wouldn't go away. Everything booted right away without flashing but just looked messed up.
Funny you should mention the Master System as I think you've reminded me that one of the systems I had needed to have the cart connector resoldered to the board as it couldn't boot cartridge games. Assuming my memory is accurate and it actually happened. It was a repairable fault though. I found a TG16 with a broken RF output once, and a defective copy of Keith Courage with messed up graphics.
The slim PS2 has a laptop quality disc drive, it's not exactly that durable with heavy usage. As for the GBA SP, I've come across various systems with dead backlights/frontlights, dead shoulder buttons, bloated batteries, a mostly dead system board that only worked if you applied pressure a certain way, horribly scratched up screens, etc.
Really I can't think of a console that's completely durable as I've always come across defective ones at some point, but the Atari 2600 comes to mind in terms of top reliability. Most just work fine and considering the age of most consoles it says something.