You have just names some great coasters! How could you put any of them under the category of 'worst'?
Because those are the "worst" coasters I have ridden from that manufacturer. None of them are bad, they are still amazing rides! Krake is in my top 10, but it is the "worst" B&M I've been on (Black Mamba, OzIris, Flug Der Dämonen, Baron 1898 are better than Krake, IMO). The same reasoning for Intamin and GCI. I have only ridden two GCI's, Troy and J&DD, and I think Troy is better. So that makes J&DD the "worst" GCI I have been on, not meaning it to be a bad ride at all..