After checking out Season 10 last year on Blu, I got myself the first 8 seasons on DVD as a Christmas present. Didn't realise it was the anniversary year, but have been rewatching them gradually this year and so far have got up to Series 3.
It's rare for me to enjoy a comedy twice. The second time around most shows are just cheesy and cause my teeth to grind at the predictability of the gags, and the constructed by committee feel. But watching Red Dwarf again after some ten or more years, I really think it's funnier than when I first watched it.
I liked Series 10, but Series 1 and 2 are still my favourites, mostly because of the claustrophobic sitcom feel to them. Series 3 onwards changed the character balance and opened the premise out, and they are fundamentally just as good, if not better than the first two series, but they are also fundamentally different from the shows I first watched, which is why I like them a little less. But everything up to Series 6 is still comic genius.
I'm not looking forward to watching Series 7 and 8 again though.