When it comes to the games, the NES/SNES era is where it is at (I will also include Sega systems in there). Back in the NES days, just about every great game was using brand new and innovative concepts that would shape all future console generations. When the SNES/Genesis came along, those gaming concepts that were made during the NES were innovated further to make games that were much better than their NES counterparts.
I guess what I am trying to say is that during the NES/SNES era, everything seemed new and exciting. Every generation after that seems much less innovative. That is why I think they have the best library for it's time.
Of course if you hold the NES/SNES games up to todays standards, they won't do so well, but I don't think that is what the OP was meaning.
