X-Box has one major advantage over GC besides the online factor, its called dvd player and it can save songs onto the built in hardisk which IMO is godly but i havent played the gamecube so i dont know.
beyond the hardware mostly all the GC people care about is the franchises, developers, and nintendo licensed characters...
which in my view makes for a very biased opinion which upon them playing a great game on another console they would shortfall it and not give it a very worthy rating.