Yankees-Red Sox is awful at the moment, games all go for four and a half hours and both teams have been average for quite a while. But continue, please.
I'm not contending that this rivalry is amazing, in fact over the last few years the only AFL games I really watch consistently outside of Demons games are the Cats-Hawks games, but to declare it clearly the best rivalry in world sports isn't just wrong, you don't watch enough different sports in enough different countries to judge. There are so many sports rivalries out there that produce amazing quality and have been running for a hundred years, rivalries that are like street gangs with the way they're bred into kids when they're born. Burgey mentioned the Barcelona-Madrid rivalry, what about the Boca Juniors-River Plate matches in Argentina or hell, what about the City-United rivalry? The 2011-12 season is probably the greatest finish to any sporting league ever, City were 8 points behind with 6 games left, closed the gap (beating United along the way) and scored two goals in the last 3 minutes of the league season to snatch the title away from United (their first since 1968).
I'm not saying any of these rivalries are clearly better, but you can't declare one the best in the world. No one has the knowledge and diverse interest in enough different cultures and sporting competitions to declare this. Your post is just hyperbole, and you know it. You could've said "If there's a better sports rivalry out there I'd be surprised" or" this is by far my favourite sports rivalry at the moment, one of the best" or anything similar to that but you deliberately declared it the clear best, admittedly probably just to troll.