I've seen all of the Expanse and to me it’s not even close. The Expanse often aptly described by critics as a poor man’s Battlestar Galactica. I wasn't a huge fan of the Expanse's fourth season on Amazon either. Don’t get me wrong. The Expanse does a lot of things right. The interplanetary politics, the interesting extraterrestrial plotline, the worldbuilding, etc. It also looks a lot better than the famously low budget BSG. It’s just that Battlestar Galactica is that rare show that completely draws you in episode by episode (water crisis, who is the cylon, election, new caprica, Baltar getting himself in trouble, famous trial episode, etc), while also having an unforgettable overarching story. And it addresses so many interesting issues along the way from politics to religion to abortion to the role of the military to so many other issues. And it just has such memorable characters and moments. I'll remember Gaius Baltar long after I forget about James Holden or Caprica Six long after I forget about Naomi Ngata. In addition, the characters in BSG all go through significant yet believable transformations over the course of the show to the point that if you rewatch the pilot after watching the finale it's kind of incredible to see how much the characters changed. Plus the musical score is up there with any tv show. The Expanse is a pretty good sci fi show, but the BSG remake is considered one of the greatest shows ever made for a reason (one of Sepinwall's ten golden age tv shows, one of TV Guide's and TIME's best shows of all time, IGN's best sci fi show ever, etc).