2. New York Yankees
Obviously the New York Yankees are going to make the list. Perhaps the most intense rivalry outside of Red Sox-Yankees, at least at the moment, is Astros-Yankees. New York has made the American League Championship Series three times in that last seven seasons, but each time, the Yankees have been bounced by Jose Altuve and the Astros.
The Astros' sign stealing scandal of 2017 only adds more fuel to the fire, as Yankees fans will erupt with chants of, "Cheaters, cheaters, cheaters!" But that's like water off a duck's back for the Houston faithful. After all, in 2022, the Astros swept the Yankees right out of the postseason without a lick of controversy.
The fans in New York, just like the those up the way in Boston, are becoming increasingly frustrated by the Astros' dominance over the last several seasons. After 2019's playoff exit, the Yankees signed Gerrit Cole to a massive free agent contract. But Cole's presence wasn't enough to put the Yankees over the top in 2022.
Brian Cashman decided to go all in this offseason and swung a trade for Juan Soto. Maybe he's the missing piece. The Yankees are hopeful that will be enough to get them back to the World Series; a place they haven't been since 2009. That was so long ago, the Astros were still in the National League.
Astros fans can be sure that if there was one organization and fanbase who hated hearing that Jose Altuve was headed back to Houston, it was the Yankees. Much like the Michael Jordan-led Chicago Bulls did to the New York Knicks during the early-90s, the Astros have kept the Yankees from advancing in the postseason. The Astros are the Yankees' kryptonite.