There aren’t many of the classics I haven’t watched to death.
Farscape, I have seen too many times. The re-imagined BSG is my all time favourite, I have seen it more than too many times.
Right now, I am watching TOS. It is good. After that, I have been considering seeing the first three seasons of Andromeda again, or continue with B5 after the shadow war, which I haven’t seen since I was young. DS9 is an option, because I have only watched the whole thing once.
My preference is for ship-based shows, but a space station will do in a pinch.
The Expanse deserves to be highlighted more. God damn it is so good. Just bear in mind that season 1 is their worst rated season. All other seasons scored above 90% on rotten tomatoes from both viewers and critics. A couple seasons scorred literally 100%. It is so damn good. You just need to get through the only somewhat good, first season.