Adventure of the week is a little hard to dismiss when it comes to most TV shows, even BSG had it's filler episodes, as much as I thought it was great sci-fi. All I can really say is I loved both BSG and The Expanse and enjoyed these shows too:
Farscape: Great show with one of, if not the, best villain I've ever seen on TV, possibly even the big screen, Scorpy is amazing.
Firefly: Serenity to finish it, can't go wrong, shame it didn't get the seasons it deserved.
Dark Matter & Killjoys: Very well done budget sci-fi, good shows, Dark Matter is closer to the rag-tag crew thrown together.
Stargate Universe: Preferred this to other Stargates, even though they're all decent. Bobby Carlyle & Louis Ferreira are very good in it. Another 'shame it was canned' scenario. Worth a watch though.
There's quite a few other shows that might come good, aren't space sci-fi or simply have their problems but are enjoyable nevertheless. Westworld, Colony, 12 Monkeys, Terminator: Sarah Connor Chronicles, Caprica, Defiance, The 100. Dark Angel was a good show back in the day, as was Sliders (I know, adventure of the week). For a laugh Red Dwarf is a must for any sci-fi fan and Lexx is a riot.
Unfortunately there's not too much like The Expanse, nor enough sci-fi shows in general, but whatever you do stay well clear of Falling Skies. There is the notion 'it has to be seen to be believed', but it's really not worth it, disastrous writing and direction ruined a show with a good cast and good premise.

Babylon 5 comes to mind, it's old but it matches the scope and detail to character, story, developement.

Couple I'd reccomend;
Firefly, as mentioned.
Stargate SGU.
It is not 'great' but it's also not as corny as the other Stargate series, quite a bit more gritty. It also has some nifty science nerd parts. Hey, it must have been good, they canceled it!
Dark Matter is on it's 2nd season. It's pretty basic sci fi, but the budgets seem to be getting better after the first half of the first season. And the writing/acting are maturing as well.
If nothing else it's a not too heavy sci fi show to watch after work.
The old Star Trek Deep Space 9 is pretty good. It starts off corny, but quickly gets dark and complicated. There are a few zany episodes that will make you want to OD on xanax But for the most part its a slow burner with various intrigues and sub plots. Not Game of Thrones, but not Cowboy Captain Kirk either.
Hate to go there but I will, the current Doctor Who is not half bad.
It's actually more of a horror sci fi show than strict sci fi. But production values are not shabby, and writing/acting are decent. It's also quite a bit more fatalistic and dark than Tom Bakers DW. I mean, the whole Rory/Am thing how sad is that?
Not live action or in space, but the Anime series 'Ghost in the Shell' has a similar Bladerunner kind of vibe to it. Great animation and some pretty tight writing.
Justwatch it before the Scarjo live action version ruins it for you.

Black Mirror is the best scifi series currently airing imo

Babylon 5 While a bit dated is some of the best Space Sci-Fi i have ever seen. And it's an arc type story like the Expanse. Babylon 5 is Must see sci-fi for anyone who follows the genre.

Hmm, no one mentioning "Space: Above and Beyond"? ..been years but pretty sure IT wasn't in "Adventure of the week" style.. ALAS afik it's another cancelled series..?
And now that these forums are getting cancelled - Who gives a FRAG and #&%"(cursing in chinese)
Fly well and fast sci/fi-IMDBs and fight those big companies!

The only other space sci-fi series I can think of in this decade are Dark Matter and Killjoys(both just finished season 2). But they are not as good as the Expanse.
In the 2000s, you could technically say all the Stargate series, though SGU and Atlantis are fairly campy(SG1 is better, but both are campy in a good way), and Stargate: Universe is darker in tone, but somewhat episodic. You also have Andromeda which is pretty campy(often not in a good way). Farscape is another space sci-fi which is fantastic if you can appreciate a show that pokes fun at itself, and the genre.
Space Above and Beyond is a great series I recommend from the 90s. It only got one season unfortunately. It was a ahead of its time. It'd probably play pretty well if it was aired today. Similar to how BSG was like contemporary military in space, so was SAaB. And based on what you seem to be looking for, I think you should check it out.
Dr. Who might count as a space sci-fi depending on your perspective. And then of course there's Trek and B5, along with their various spinoffs. B5 is definitely all about a series through-line.
Off the top of my head that pretty much covers space sci-fi for the last 3 decades.

Farscape, Defiance.

I liked Andromeda & Farscape but probably not something you will want based on your last statement.

Oldies but goodies include.
Babylon 5
Space 1999
Blake's 7

For a cheesy bit of fun from back in the day, check out
UFO (1970)
.
Free here (US):
https://view.yahoo.com/show/ufo

I've seen a lot of people mentioning Firefly/Serenity & ST DS9 (all of which I love) but haven't seen anyone mentioning Farscape. I think you can watch it on Netflix (last I checked). It's older but it's got great characters, story, and such imaginative aliens (puppets).

Of ones currently on TV I'd say check out Orphan Black. Great show about clones. Helps if you don't mind some feminist undertones.
The lead actress is Tatiana Maslany who finally won her Emmy for playing 11 clones give or take.
Take that under consideration, as it may be a first, A sci-fi show winning for best actress. How often do you see sci-fi get that kind of respect? All due to the actress.
Plus it has good action, humor and a fast paced story. If you chose to watch it, make sure you at least watch the first 3-5 episodes as some people take that long to get the full story set up. I was hooked from the first scene, but again, it takes about 5 episodes to get the full back story, plus episode 4 is the first one clone(played by Tat) impersonating another clone(played by Tat) that shows the extent of Tatiana's acting expertise and you will agree that she should have won all the Emmy's. Sixth episode she flipped it with another cone impersonating a clone scene that was hilarious and a bit of slapstick too.
First couple of years she did not get nominated and twitter went ballistic, third year finally a nom but not a win, and finally, 4th year she won.