Vintage Batman villains!
Oh definitely the Study series.
Poison Study was so so so so good! I couldn't sleep, I just stayed awake listening to the first book. I literally hung on every word waiting to find out what happened next.
And then everything after it just got worse and worse. The rest of the books in the series aren't great and I actually hated them for a while. BUT THEN I read the Glass series and realized how lucky we got with the rest of the Study series.
Seriously the Glass series is AWFUL. Read Poison Study because it is fantastic, but then never read another Snyder book again.