Oh, okay... too bad about
Yunketsu no Maria. I still had that one in the back of my head as something to take a look at. How exactly did it jump the shark?
Akatsuki no Yona simply didn't catch my attention as much as I hoped at the start of the season.
Aldnoah Zero... well, it certainly did drop a lot of its narrative threads from season one, as if the writers simply lost interest (Rayet, Marito, Inko, basically all the secondary characters got their mini-arcs dropped). Their focus seemed to be on the wrong kind of story, compared to season one, with that irrational rivalry between Inaho and Slaine (which was mostly one-sided, anyway, since Inaho couldn't give a crap). But I still thought that the basic narrative was solidly told, nothing which can be sneezed at in this age of moe-blobs and harem antics.
Also, the soundtrack was vastly inferior to S1, with a lot of recycling and no new stand-out songs. It's bit as if the writers themselves were surprised that they got a second season.