Firefly was pretty decent. Serenity, too. But as space drama series go, neither come close to The Expanse.
Just the attention to little details, practical adaptations, on The Expanse is amazing. There's no gravity in space, so characters routinely wear magnetically-capable boots, practical in what are often metallic, industrial environments. And where there is gravity, it can be employed as a weapon. Ships don't fire lasers or bullets, they have magnetically-charged rail guns. The food apparently sucks.
One thing I often wonder about in many space dramas is how inhabitants of these largely metallic space ships often seem to operate in living-room comfort when metals usually conduct cold efficiently and space is as cold as it gets.
