Return to Arkham.
Batman: Arkham Knight was a great game, but in the end, for a lot of players, all it did was make them miss the far superior Arkham games that had been released on the previous generation, and were entirely unplayable on the current generation of consoles- Arkham Asylum and Arkham City are both frequently cited as better games than Knight, and even Origins is considered to be pretty good.
So if you wanted to play through those games – again, or for the first time – you may be in luck. According to a tip that Eurogamer have received, Batman: Return to Arkham will be launching on PS4 and Xbox One in June. The collection will include Arkham Asylum and Arkham City (though not Arkham Origins), both with upgraded visuals, and all DLC included. The collection has also been rated by European game rating board PEGI.
So, yes- if Knight disappointed you, you are highly encouraged to give Asylum and City a go. Maybe then you will understand what the big deal was about the series in the first place.