Tough question. However unlike Glenn above, I didn't see "a proper story arc" as totally a good thing. On the comedy side of things, one reason that the Young Ones worked as a sitcom I think was the hopelessness of their existence (relatively). On the Young Ones, there were 4 blokes stuck in a house having to live with each other and with little purpose in their life. (Aside from occasional character obviously). Red Dwarf was similar to this up until series VI where as you say Glenn the characters suddenly had a purpose in their life (finding the ship). RD lost something for me at this point and tbh I haven't seen VII and VIII I think. My top 3 in this order would be IV, V, and II. Which probably means that I like the sci-fi more than I'm admitting. I enjoyed BTE anyway.