I really enjoyed Forty Millenniums of Cultivation
It's a (3000 chapter!) sci/fi cultivation fic written by a Chinese communist who drinks their respect women juice.
It discusses a lot of concepts in really interesting ways, has good and believable character development, and has a beautiful, hopeful, message, and regular scenery tearing xianxia mecha space battles with the fate of the universe at stake.
been recommending this one a lot