I think that XBox's line up was stronger because of the number of choices. A number of the games might not have been that great, but at least they were there to rent and try out for yourself.
The Gamecube on the other hand basically had its launch line up and then... Res Evil months later. That is poor planning. SSBM and Rougue Leader may be 2 good to great titles (I'll just say great since I've never played them so they deserve the benefit of the doubt) but it's not much to tide you over a few months.
I would rather have mildly entertaining games to play for a stretch than nothing, which was the alternative that Nintendo gave you.
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