What's the coolest series of Lego that is no longer produced?

For me it's Power Miners that was such cool idea of miners going deep into the earth cluster to find the reason of earthquake and encounter hostile creatures. Machines were amazing, sets were really cool and you could combine them and they even gave you a comics in instruction to show how the story goes. I heard that they stopped it because 2nd round sold badly because of non existing marketing but 1st and 3rd sold really well and if all 3 rounds don't sell then the series is canned. What is...