Feel like this is a bit of cheating. But
Firefly and
The Mandalorian were really well done but we've also only had one and two seasons of these shows respectively.
Firefly, for what Joss Whedon was trying to do in making a Space Western with the themes of Rebels and Freedom and the like, did a near perfect job of bringing his vision onto screen. It worked in almost every way. Make no mistake, the television series itself wasn't perfect, but the way the show fulfilled the vision and themes it was trying to present was pretty close to perfect, regardless of any potentially substandard episodes though even those were far and few between. So the concept of
Firefly was great and the cast was perfectly amazing. And the movie was pretty good too.
The Mandalorian meanwhile seemed to singlehandedly drag Star Wars out of the rut it was in since
The Last Jedi since it was able to present a proper Star Wars story with all of the atmosphere and nostalgia that the fandom appreciates and yet still be it's own thing, independent of the whole Jedi-Sith dynamic that has dominated the movies and is almost a narrative trap for Star Wars nowadays. I feel the first season was better then the second, but the latter was still pretty good. I think the only danger with
Mandalorian is it might drift less into nostalgia nad more into fan service which isn't a problem for me, but was for many people who for some reason beyond my comprehension didn't like R
ogue One.
Now right below, in the 'Good' category are actually three sci-fi series that I actually think are ironic when it comes to Science Fiction in general and especially on television. Quality wise, Firefly and The Mandalorian are better overall then these series but I feel that
Babylon 5, Star Trek: The Next Generation and
Stargate SG-1 are literal titans of Sci-Fi on TV and furthermore to their credit, were able to uphold a standard of quality over multiple years. Maybe The Mandalorian can join them someday, we'll see but as is, despite being a tier below in quality, I feel these shows are far 'greater' in their cultural impact.
Star Trek: The Next Generation is a show that as a kid I barely had any interest in but watching it as an adult all the way through, I really appreciated what they did and how big a deal it must've been. The original
Star Trek series, it never appealed to me whether it was too dated or just a little bit too hamfisted or even campy. But
TNG, especially the middle seasons, were just great television overall. I loved the themes and it was refreshing seeing a television series that was based on episode by episode content instead of the common meta-plot arcs that span across seasons now. And it explored so much as well. It actually mitigated a lot of the stereotypes I held about Star Trek being a bunch of pajama wearing pacifists... though they are still a bunch of weenie pajama wearing pacifists, they still manage to make it work and did so for most of the seven seasons it was running.
Babylon 5 was quite an achievement in that JMS was able to produce five seasons (or rather 4.5 seasons
) and was able to bring it to life on television. They basically executed his entire
LOTR style saga in space and it worked 95% of the time. You had a diverse collection of alien governments and organizations with back histories and cultures and a galactic history that went back a thousand years and were able to introduce things like time travel, galactic governments, telepathy, genocide, ancient aliens, racism, politics, civil strife and so much more and weave it all together into an amazing story. It did
Mass Effects Citadel before
Mass Effect and in a far better and more mature manner as well. The only real knocks against it are more then a few episodes were weak, and some of the acting wasn't even on par with its rival shows like in
Star Trek.
Babylon 5 for me is actually superior to
The Next Generation IMHO and even
Stargate SG-1 because it had a whole narrative thread and it executed it and while I love episodic shows (because they tend to be more original now) having an overall narrative and plot is a clear advantage nonetheless. And Babylon 5 executed it very well from beginning to end.
Stargate SG-1 despite being on for ten seasons and having a successful spinoff and several movies for some reason feels like a sleeper still. For whatever reason it never seemed to elevate beyond the SciFi Subculture like
Star Trek or
Star Wars has. Sometimes I feel like even the new
Battlestar Galactica had a larger impact on pop culture, which is unfortunate.
Stargate SG-1 managed to deliver ten seasons of quality. It had a super novel concept based off of the movie and the main cast was amazing, even as it evolved in later seasons. I don't feel anything was as ground breaking as with
The Next Generation or
Babylon 5 but it was easily just as good as those shows overall and oftentimes I felt the stories (episodic ones especially) were often just as strong.
Babylon 5 meanwhile might've had a better overall storyline, but
Stargate SG-1 was a pretty close second and went through several strong plot threads before the so-so Ori one finished off the series. Great show overall.
All three of these shows I feel are worthy of emulation and seen as examples of what sci-fi should be.
As for the decent category... I liked all of these series but... I don't think they were as iconic as the ones above them, or as condensed in pure quality as the S-tier.
Andromeda was a good series that I'm still (re)watching and
talked about a lot already so I won't do it again here.
Battlestar Galactica's reimagination could've been great but after the first two seasons it became a massive disappointment to me. It felt like so much squandered potential that I think after the third season or something I just stopped watching it. You could literally tell the Writers had just run out of material which is so sad and pathetic I almost felt like dumping it in the bottom half of shows. The whole thing started by shit like
Lost seems absolutely terrible for screenwriting, just leading television series into nonsensical cul de sacs creatively. But the first two seasons were quite strong and some of the best Sci Fi period.
Farscape was so novel and original that it's quality is undeniable. Such amazing characters and wild storylines, everytime I saw a new episode I wondered how John Crichton could maintain his sanity in space. It was so wild and trippy everytime and yet somehow they made it work. With that said, it got so into itself that I feel it was convoluted to the point I actually struggled to keep track of things and even maintain my interest. Might just be personal taste but while I thought it was decent, I can't say it was unequivocally good. Still a great show with how inventive and creative and daring and original it was.
Space: Above and Beyond is almost a B-minus but dammit, all of its flaws aside... we need more MilSF! Plus it was only one season, which is tragic.
Star Trek: Deep Space Nine would've replaced
TNG in the A-tier a few years ago but after rewatching both series, I'm switching them around. Deep Space Nine has all of the advantages I talked about earlier. Strong characters and an overall narrative and plot throughout the seasons and unlike the weenie TNG Federation, the DS9 is far more gritty. But... watching it again I think I was dazzled by the politics and explosions and the fact that Sisko's Federation was just rougher. Watching it again now, it just didn't strike me as being quite as ironic as
TNG was. It's stand alone episodes were often weaker and when I compare it to
Babylon 5, it's acting was better then B5 but the story overall... was not. Almost everything regarding the Founders and Pah'wraiths and Sisko as the Emissary just fell flat to me. Very good series, maybe the best of this tier, but not iconic like the ones above it.
Stargate Atlantis, I feel scared putting it here but... I just didn't like it as much. It's odd because it was far tighter then
Stargate SG-1 and other series but it still felt too rounded around the edges. The main cast including Sheppard never really appealed to me like Jack O'Neill did, or even Cameron Mitchell as a lead. In fact character for character, I liked the SG-1's better. I also thought the Goa'uld and the Replicators were far more interesting then the Space Vampires... uhhhh the Wraith... I forget their name and the Asurans. Certainly not bad, but I feel it's a tier below the other shows.
Star Trek: Voyager. I tried re-watching this and I think I liked it more as a kid because a lot of the episodes were indeterminably boring. It feels directionless and the use of technobabble is far more pronounced and noticeable and painfully cringe here then in previous series. With
TNG and
DS9 it never became this much of a distraction. Combine that with the fact none of the characters really stand out to me like the ones in previous series, the episodic content, despite being on the other side of the galaxy, isn't as strong as that from
TNG IMHO, and the fact that the show was so softball with the concept of being stranded on the other side of the galaxy it led to the meme 'Voyager Reset Button' all meant to me that this show was just poorly implemented.
Battlestar Galactica even did the survival thing better. Anything Voyager tries to do, someone else did better. It even neutered the Borg... ugh... With that said, it wasn't universally terrible, but it was still disappointing. Episodes like
Year of Hell, Equinox and
Living Witness gave some clues as to the potential the series could've been, but never came close to achieving.