The MCU and GoT are very similar, in that they were both the biggest-ever franchises in their mediums of film and television, respectively, with unlimited budgets for superlative spectacles, both had massive universes with tons of likable characters, and both had decade-long storylines that made them pop culture events . GOT at it's best had far better writing than the MCU, but at it's worst was far more unwatchable than the lamest Marvel movie.
Of course the difference is in how both franchises concluded. Endgame, while not the best film ever, was still satisfying for the fans, whereas GoT final season was a nightmare to watch. What should be taken into account is that whereas the MCU is based off of Marvel Comics, which has a decades-old library of thousands of stories to adapt, GoT was based off an incomplete story by GRRM, so the MCU had it easier in terms of adapting from the source material vs having to create new plotlines. Also, the MCU is primarily a kids franchise, so it's plot holes are far more forgivable. That being stated, it definitely feels as though Kevin Feige is far more competent and faithful at adapting stories than D&D, not mention, Feige knows how to hire good directors, whereas GRRM's dumbass chose to hire D&D because they knew Jon's lineage.
So to summarize, the MCU wins because it's finale was (not great but) satisfying, whereas GoT's was godawful, but both franchises should be respected for being the undisputed titans of their entertainment mediums and putting on some of the best spectacles of the 21st century.