let's break down the reasons
Matt: emo boy throughout the first show. Frequently paranoid and always trying to make it so he was the only one to take care of his little brother. Always tried to get into his little brother's pants. Ultimately betrayed the other digidestined based on baseless facts presented by the enemy and later went on an emo journey to "find himself". Later fucked Sora with absolutely no regards for how Tai felt about her.
Sora: Turned into a grade-A pussy in the second season as opposed to the tomboy attitude from the first. Flat out abandoned Tai for the prettyboy emo rocker.
Long answer short, hate em both, more than enough reason to, but Matt fucked up more.