I do like this one. Related, I also like the series a few years later with Calvin and Susie haggling over how much it'd cost for him to eat a worm.
But these are personal preferences, not a list of an objective "best" comics. For example, a lot of folks really love the artwork of the dinosaurs, or space, or a lot of the other scenes that Watterson draws. They like being drawn into Calvin's imaginative world, and I totally understand that. But for me the "daydream" comics don't make it onto my list, and that's not to say they aren't great.
But these are personal preferences, not a list of an objective "best" comics. For example, a lot of folks really love the artwork of the dinosaurs, or space, or a lot of the other scenes that Watterson draws. They like being drawn into Calvin's imaginative world, and I totally understand that. But for me the "daydream" comics don't make it onto my list, and that's not to say they aren't great.