To me, the most controversial and garbage one is without question Redo of Healer. Wanted to cleanse my sole after just an episode and was absolutely unwilling to give it my standard 3-episode watch before making a decision on it. Absolute worst. However, the anime that comes to mind First (possibly bc I try to forget the above mentioned at all cost) is Nanna. I loved that show so much and watched religiously only to never, Ever get a final episode?! Dispute the 49 other good episodes, the frustration has never left me, and it still haunts my existence even now.