[justsomeguy]

If we're going to keep count, then I'll nominate the following:
1) HnG Can't Take My Eyes Off You - not only is it not the anticipated continuation from the second season's ending into the most brilliant part of the manga (which ass made this business decision?), Manglobe's art is terrible, the humor is lacking, gags and references have devolved into outright namedropping, some eps are recycled from earlier parts of the manga into a different (worse) context, I dislike Ruka and her Greek chorus, the ongoing drudge the manga has been going through the past couple of years, the possibility that Hata will write this out of canon when the manga reaches this time point, the possibility that the low sales and poor reception will prevent any more anime of this franchise (and hence no End of the World or Greece arc), etc etc. Basically, everything that can go wrong is.
2) Dog Days' - it's not the lack of plot itself, but rather that the lack of plot led to lack of context/framework for the characters, of which now there are way too many, which will lead to problems in the future if Nanoha was any indication.
3) Little Busters - right now, there's next to no storyline, and some of the standalone episodes are boring
4) Seitokai no Ichizon Lvl II - not only are the characterization and character dynamics different, which negatively affected the humor, the directing and artstyle lack the life of the first season and feel cheap. DEEN > AIC, WTF.
5) Kore wa Zombie desu ka? OF THE DEAD - mostly forgettable, since much of the humor was copy-pasted from the first season; only two eps had anything to do with the big storyline; too short at only 10 aired eps with 2 OVAs.
6) Kokoro Connect - not only was it bland, not just in characters but also in art (surprising for SilverLink), I had issues with the base concept of character development through the direct interference of an alien being (considering nobody can do anything about it, it's basically deus ex machina).

There are some shows that were worse, but didn't qualify because I had no expectations at all. And as for Another, while it wasn't "good" it didn't disappoint me because I saw the whole thing as a brilliant joke, with the last two eps being the epic punchline.