o Firefly - no brainer.  Brilliant.
   o Battlestar Galactica  - Has some issues mid-late course, but still pretty end-end enthralling.
   o Dark (I keep re-watching this over and over every few months.  I have many notebook pages full of analysis.  Seriously good SciFi for the most part.)
   o Altered Carbon (mostly Season 1 - but Season 2 was okay)

Not really science fiction (even bigger themes explored) but far superior in terms of overall quality of work/screen writing, and has a similar "concept" that a lot of supposed science fiction shows have - "The Leftovers" - Which I put on my list of the 5 most brilliant things on Television (Sopranos/The Wire/Deadwood/Breaking Bad being the other 4).

I'll give a honorable mention to stuff I loved but I can't totally recommends:

   o Travelers - I'm a sucker for a good Time Travel Show. 
   o Foundation - Pretty - I watch it, but I totally would never recommend it.
   o Fringe - Wow -  was totally into this.  Definitely an acquired taste though.
   o Raised By Wolves - Interested in where it's going.  Could entirely suck eventually I guess. 
   o Black Mirror - Hit and miss, though hits often enough that I keep coming back to it.
   o WestWorld - I mean, we all watched it.  Season 1 was *awesome* if you watched it in realtime and didn't read all the internet commentary when the aha moment hit you.  Season 2 was pretty good as well IMHO.  Season 3 was just dreck where the screen writing tanked *but* it paid an *awesome* homage to the very last of the Foundation Novels to bring it all home.