A friend who knows my tastes really well recommended Attack on Titan (mostly for the pacing) and I ended up really liking it. Although there were a few slow parts and I could see almost every plot twist coming from a mile away I still had fun watching.
The premise is that humans live inside sets of walls and walls within walls to protect themselves from Titans. Titans are giants that seem to only have one purpose... eating people. So, humanity has lived safely within these walls for years but Attack on Titan kicks off with an attack on the walls that's successful. Titans stream in and start killing people.
The series continues from there and gets interesting once the main characters have a bit of a time jump and join the military to fight back.
The action scenes were a lot of fun and actually had lots of movement. That's been one of my criticisms of so much anime I've tried, it's just still pictures while characters waste time. Attack on Titan felt much more fluid and visceral than that.
My main complaint is that nothing is actually answered in the end. It just stops but without wrapping up most of the loose threads. Everything is left basically unanswered and it feels like it needs an immediate follow up season of the show. From what I understand, there will be one eventually but it's already been years and it's no where in sight.