I don't know if you've seen it already but I can recommend watching all the Starship Troopers films. A lot of people have watched the first one but the follow ups are great as well. The acting is not Oscar worthy but you'll have a great time. Plus they often have a cheeky society critical undertone.

If you read manga I can recommend Plantes by Makoto Yukimura. It's about a clean up service in space combined with some settler colonialism versus terrorism.

Babylon 5. Despite when it was made (in the immediate aftermath of the end of the USSR and all that "end of history" nonsense) it's got a lot of remarkably good takes that aged very well. The show's creator is a student of history. A running theme through the series is "fascists can't be negotiated with, they need to get walled". The show's creator wrote almost all the episodes: 92 out of 110. And most of the ones he didn't write were early in the show's run. Characters just got more and more consistently-well-written as the show went on. The series has a very definitive and satisfying and heart-wrenching finale. This ain't no "Star Trek: Enterprise".

There's also a major theme of respect for others' religions despite the show's creator being an atheist. He's not one of those "new atheist" assholes. His attitude is more "If faith brings someone comfort, and they're not using it as an excuse to harm others, I got no problem with it". The best episode of the series (in my opinion) is entitled "Passing Through Gethsemane", and handles a unique kind of crisis of faith by a Catholic Trappist monk with respect and compassion. A spoiler-free clip of my favourite scene from that episode.

Skip the original made-for-TV-movie pilot "The Gathering". It's not bad at all, it's actually pretty decent. But so much changed between that pilot and the TV series that it's basically an alternate universe. It's worth watching after finishing the series though, as a sort of "what if?" thing.

The first season is rough, but not as rough as its reputation would have you think. I'd put it about on par with the first season of Deep Space 9 in that respect. Skip the episode "TKO" though. It's the "Spock's Brain" of B5. You're missing nothing.

Short version, it's got a lot of consistent themes that left-leaning folks tend to like. Labour solidarity, the problems with aristocracies, the problems with capitalism, the problems with military-industrial complexes, how easily fascism can take root if not continuously weeded out, the dangers of propaganda, the dangers of wishing for a "return" to "the good old days" of empire, the need for compassion and material aid to those who might not be "like us", etc.