I have started with Battlefield in 2016 and I really have to admit that I loved the game. I mean I cannot really evaluate any of the previous games before it, simply because I have not played them or at least I did not play them much.
What I really liked about Battlefield 1 was the level of immersion. You really felt like in a war running through maps like Argonne Forest, etc. Also I really enjoyed playing with those older and often very crude and experimental weapons - I found them quite exciting. Moreover I personally think that Battlefield 1 was a relaxing and less try hard experience. You could simply have a fun time there, it was way less frustrating than the games coming afterwards in my opinion.
Nevertheless I also know that it had its flaws like random bullet spread, elites, sweet-spot mechanics (even tho they were fun when sniping myself) or suppression causing your bullets to go everywhere.
Still I enjoyed the game, it felt well-conceived and the design went in one clear direction. It was very casual but it went casual all the way trough. It had its own art style and I enjoyed it a lot. Nowadays DICE unfortunately has taken the role of a copier trying to combine several game directions which obviously does not work out.