If you want per capita (as in which classic system has the largest percentage of highly rated games by players over the total number of games released on it), then the answer is the Nintendo 64. Sure, it only has somewhere around 400 titles, but it holds the highest concentration of highly rated games over any other console. The runner-up is the venerable Dreamcast.
Now, if you just want the greatest number of highly rated games, then your answer is the Playstation 2. The PS2 had over 4,000 games released on it and, with it being 100% fully backward compatible (remember when we thought that was the future?) with the original Playstation's over 3,000 games, it has the largest library of good games by volume alone. Of course, that also means that both Sony systems are also bloated by some of the worst games made, but that's what happens when you go by volume.