All of seasons II to VI were brilliant for me,but seeing as I have to choose Season VI would just win my vote,for classic episodes like "Rimmerworld", "Gunmen Of The Apocalypse" and "Psirens".
In general I would say that Season VII was fine until Chris Barrie baled (and unlikely that "our" Rimmer could take over as Ace) and Kochansky took his place.The whole dynamic was ruined and although the rest of the episodes weren't disasters they were never quite as good.Season VII was poor....
Kryten is my favourite character.
Cat: "Forget red - let's go all the way up to brown alert!"
Kryten: "There's no such thing as a brown alert sir."
Cat: "You won't be saying that in a minute!"