I never got to put in my 2 cents but I finished the game this weekend at 100%, currently just taking a break before I finish getting the platinum so that I can play New Game + with new skins (hope they come out soon).
But this is definitely my favorite game of the series. Arkham City is great but having replayed it before starting Arkham Knight I feel the upgrade from Asylum is what made it so special. The gameplay in both are solid but the story in City is nothing to write home as it felt more like Batman going around fetching objects for a cure. Origins was certainly intriguing as well and I put it right there with City overall, but the quality of that game hurts it a lot.
My expectations were certainly met and the Batmobile is the highlight of the game for me. Battle Mode is amazing and once I got a handle on the car I couldn't get enough of it. I love how they incorporated it too with transporting criminals to jail or civilians to safety. Now I just wonder what it's like back there, hopefully not pitch black dark.... maybe TV? Magazines? Sun roof?
I loved the raised threat level with an actual army overtaking and patrolling the streets of Gotham instead of just random groups of thugs that you beat down. I would have found
that tedious if I needed to just continuously do predator or combat rooms after 3 games of it. So I loved the extra variety and they were very well done. The whole "It's time to go to war" angle was awesome and a nice touch to the game. The drone battles never felt tedious to me actually and were some of my favorite sections of the game. I loved teaming up with [BLACKOUT]Oracle[/BLACKOUT] in tank battles near the end as well. Being able to work/interact with Robin and Nightwing at certain points was great as well.
I think an improved boss fight with AK could have really hit home especially after the reveal. It was decent and I was Ok with the big bulldozer chase because the guy was getting so desperate to kill Batman but adding some extra hand-to-hand up close and personal would have made it much better. I'm sure a tank battle or 2 in the main story could have been scratched out or replaced with something else but I'm not gonna raise hell about it, boss battles in this series have never been their strongest suit and they tried something different this time around. I wish Two-Face was utilized more as well, with him and Bruce having history they could have given him more to do and make it more personal but he was merely a predator room side mission.
If I could rank them I'd say for me it's
Arkham Knight
Arkham City
Arkham Origins
Arkham Asylum
It's weird putting these games below each other because I think they're all great. It's not like Asylum is the "worst" to me, just the "least best"

(The only thing worse about any of these games is the quality of Origins and the crippling bugs I had to deal with in that) I could definitely go on and on about what I liked/disliked about the game but that's about the gist of it for now.
Every game's improvement is also the result of the previous game as well. So all the refined gameplay elements from AK came because they did such a fine job with the previous ones.

However, the job they did with the Batmobile was
incredible and I think they did a tremendous job overall with AK and it's unfortunate that this will be the only game we get this Batmobile. Only thing missing was being able to drive to the Batcave.
Or if you wanna get old school...
And maybe the Batpod with the cape flowing in the wind. And a

cameo.

Oh well, can't have everything.