The best you can do in a thread like this is to get two people to cede enough points to each other that it is found that both first parties are highly regarded and close enough so that fighting is dumb because the decision is completely subjective. And for those who say it is always subjective, no one who doesnt belong in a psych ward would say MS's first party matches up, so their is definitely some objectivity here.
I think Sony fans want people to recognize how good Sony is in this department (some people don't even know Sony makes as many games as they do), and Ninty fans want to remind people how esteemed they've always been (they have been do quality for a long while). Can't we all just agree on this and get along? :)
This has been a PSA from the Alliance for a Better (gaming) World.