Since 95% of responses to Mars Volta being mentioned are “they went shit after Deloused” or “they went shit after Frances”, I’m going to throw in The Bedlam in Goliath and Noctourniquet, both of which are classics and top three candidates for their respective years.
The Bedlam in Goliath is basically the musical equivalent of malfunctioning strobe lights and ray guns being placed your head. I can understand why people hate it (it is kind of oppressively noisy and overwhelming to the senses) but if you spend time with it, the details and twists in the songs reveal themselves and it becomes absolutely electrifying. I can’t think of any other album like it.
And Noctourniquet is also fantastic in a different way. There’s this weird contrast between sort of relaxed vocals / music and extremely busy drums, so it ends up being very disorienting. I think it’s generally viewed as a throwaway / “they ran out of steam” album, but while it doesn’t have the explosive insanity of their early work, the tight songwriting and creativity is there. It’s a solid A.