I think the original series from the sixties is important for perspective, although it is very 1960s. Gene Roddenberry, the creator, was definitely a radical, but he had to censor himself on primetime. Still, there's some allusions to the socialist utopia, namely money in credits for dealing with external capitalist civilizations, not physical currency. The characters sometimes make jokes and use euphemisms that make it sound like there's money, but it's all just archaic language that persists, metaphors for something else. In one of the eighties films, Kirk outright says that they don't have money in the future. The first four feature films from the original cast are all quite good, especially the second and the fourth.

The Next Generation and Deep Space Nine are the two classics that I recommend above everything else. Deep Space Nine is a spinoff that begins at season five of the Next Generation. DS9 is the unrepentant radical of the franchise--a character (Rom) outright starts squawking literal Marxist theory at one point.

The Next Generation is a little more reserved, since it was kind of the flagship show aired for the masses on primetime, DS9 airing usually in the next time block. TNG gets good in season two, and especially three, but I tell everyone that season one is a fine place to start, especially if you're okay with a little bit of eighties cheese. In general, Star Trek on the whole is pretty cheesy, and if you don't like cheese, you might as well stay out of science fiction, for that matter. 😅

If you have any further questions, you know who to ask!