Circle of Land gets a variety of spells otherwise unobtainable to Druids, including Haste, Cloudkill, Cone of Cold, Invisibility (greater and otherwise), hypnotic pattern, and more. While not as flashy as the others, a CoL druid is an *excellent* party support option.
Circle of Moon, as a note folks have done literally thousands of damage with the Owlbear jump. Also your entire HP pool is effectively bonus temp HP, so you're ridiculously tanky, especially if you give it a bit of help with AC, and options exist to do so. Web off your Spider form is fantastic at providing advantage early game. While any Druid can use those abilities, none do so as well as Moon Druids thanks to the bonus action wildshape.
Circle of Spores, the summons and so forth are nice, but the armor of the sporekeeper is nicer. Being able to provide haste to your *entire party and all summons you may have* is an insane boon. It alone is good enough to make Circle of Spores Druid one of the most powerful subclasses in the game. Just 2 levels can unlock it, so there's definitely MC options there fwiw.
Tough to go wrong with Druid, they're pretty great regardless.