These are some of the ones I managed to finish or watch to a point where I figured it wouldn't get any better, and still hate and want my time refunded:
Gundam Seed Destiny -> they should have stopped at Gundam Seed.
Sword art online -> ruined by fanservice and harem garbage. I otherwise liked the idea.
Another -> when you try too hard to make a plot twist but it makes no sense.
Attack on titan -> bland and overrated. Not sure if the anime has reached the part where the magical/supernatural events just feel completely off, like just made to get the story follow a certain path. Also, everything after opening the basement door just feels cliche.
Aldnoah Zero -> plot holes and nonsense all over the place. Would still watch again for the action and soundtrack, but with several cans of beer so I can overlook the hollow characters.
Bakemonogatari -> good premise but ruined by fanservice and weird monologues.
Bleach -> I used to LOVE this series, and looking back at the first 3 seasons it just feels like a completely different anime from what it became later. Dragon Ball syndrome.