I watched the first season dubbed but changed to subs after that and haven't regretted it.
A lot of stuff sounds very cheesy in English while you don't get that same feeling while watching the sub. Although AoT's dub is decent as far as I remember, this is very rarely the case in my experience. I'd say that out of the 10-20 anime where I've tried both dub and sub, only Black Lagoon was better in dub, mostly due to having a cast of characters who were actually supposed to be from various parts of the world.
Of course, it also depends on your TV habits. If you're usually scrolling on your phone while watching, subs obviously aren't for you as they demand your full attention.