A gigantic effort indeed, from both content and implementation point of view, however not completely clean from errors so can not reach the top score.

To be precise would say that 1st and 4th seasons value 8, while 2nd and 3rd are much better and I would say 10.

In the first season Eren pursue his revenge, he is pretty monothematic (this I don't like), moreover the situation is kind out of the blue and feels not so realistic, however the animation, design from technical point of view is excellent as well as first opening theme.

In the 2nd and 3rd season the characters are more grown up and they start driving a bit the story (instead of being just shaken by it), these 2 seasons are really good.

In the 4th season the story start to twist too much, moreover one of key characters who is introduced here is totally fake (Gabi) and example of the too much trying of overexpressing characters.