I'll probably get some flak from others, but I've still never been convinced that any other video game company in the world can top Nintendo when it comes to fun, original, and timeless titles. Of course, it's impossible to say that no other game systems are worth playing, but I personally feel that the Nintendo Legacy is nearly unmatchable. Hell, I didn't even own an SNES, yet I find myself remenicing over more 16-bit Nintendo games than my own Genesis collection.
I think this is because Nintendo understands the classic formula for successful game development -- one that is easily ignored in today's game industry. Games need to be fun, intuitive, and mesmerizing. They should be addictive, but not oversimplified. Some people crazy substance, others want instant gratification. And without even traversing various genres, I think it's very possible to achieve both of those goals. If I had to pick a pinnacle for gaming, it would probably fall in the 16-bit era, though it's hard to decide on any one system or generation, because they all have such an intimate affect on each other.
I'd love to scope my answer further, but it would probably help if someone butted in their own opinion to keep the ball rolling, otherwise I'll be agreeing with myself for the next three pages!