Basically everything Paper Mario touched after SPM, with the exception of Origami King. Aside from some very rare moments those games really just don't make me feel anything positive. This includes Mario & Luigi Paper Jam, which is the most squandered potential I've ever seen in a game. New narratives and characters are really a pillar of Mario RPGs and without them they just feel... empty and sterile. Origami King may have not executed its original story as well as the early games (especially with the original characters being still very limited by the restrictions) but the fact that it's there at all puts it leagues above SS, PJ and CS and their typical Mario setups. I didn't even finish Color Splash because I'd watched the ending on YouTube and didn't feel like pushing myself through the rest of the game just to see it in-game. I stopped after finishing Snifit or Whiffit and realizing that the reward for getting a perfect score is something required for a later boss fight, and I really didn't want to get a perfect score. Heck Sticker Star and Paper Jam were probably only finished by me due to being on a handheld system and more accessible. At least Paper Jam had gameplay that was on point, but the Toad missions were such a drag.
Other than those games, every Mario vs. Donkey Kong game after the first one basically threw out the whole appeal of the original game, and its Game Boy predecessor, in favor of gameplay that's just way more boring and convoluted to me. I did beat the first DS one but wasn't impressed, though I did mess around with the level editor, a feature I really wish made it into the release of the first game (where I'd have used it far more enthusiastically). The one thing I can say I appreciate about these games is they brought back Pauline, who was incredibly rare in the 2000s & 2010s before Odyssey. Overall though, I feel like that series died after the GBA game which is a huge shame because that game was one of my favorites to play back in the day and there's so much potential in another game with that style.