Somewhat to my chagrin, the Wizard.
Not because I don't think the Wizard should be that. They absolutely should. It's literally their specialty.
Rather, because the Wizard is incredibly awful at actually supporting the FLAVOR of the class. It doesn't have a single research- or academia-related class feature. It doesn't have anything special with regard to skill or study. Literally the one and only thing it gets which isn't "Cast More Spells" is halving the gold/time costs of copying spells. Not researching--copying. The Wizard is an extremely excellent plagiarist, without a single bit of research-related content. I find this absolutely appalling. It's not like I'm asking for ultra-specialization or something really narrow and specific. This is literally the foundational concept of the class, "person who does academic research to learn spells"!