Ooh, you opened a can of worms, here. I won't write a page-length comment, as it's unlikely anyone will read this, but I have to weigh in:

I'm gonna have to say that, so far, the Nintendo 64 reigns supreme. It's for the reasons you stated - straight out of the box four-player co-op can't be beat, and while there have been many games for other systems that I've enjoyed, there are no others from which I have so many fond memories with family and friends.