Yeah, I also enjoyed Crystal (the first one I played) a good bit, then I played Yellow, and Sapphire was where I stopped.
Not a Mega Man fan, either, I just never got into it, but the situation there is a bit different. While there was a time when Capcom milked Mega Man like crazy (and now, for some reason, they like to pretend he doesn't exist), at the very least, the amount of people who will buy anything Mega Man is significantly lower. But I can see if that's the first non-Nintendo analogy to come to mind. :)
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Blitzball fan? Try Captain Tsubasa II (in English) for NES!
Game reviews/articles by me: http://betweenlifeandgames.com