Shield Hero, without a doubt.
Then beyond that, Go-Toubun no Hanayome was heavily promoted in bookstores and bluray shops, ReZero was also getting promoted, there was a gigantic Hitori Bocchi no marumaru Seikatsu advert on a building in akiba, Bandori adverts were across tokyo in general.
But Shield Hero for sure had a lot of promotion in Akiba. I just remember seeing it everywhere.