I like anime and I know ones with multiple personality/identity stories.
I have decided to list them here and grade their dissociation portrayal.
Yu-Gi-Oh!; A for original story, B for spin-off stories
Mitsume ga Tōru; B just because it has not quite sit with me
DNA2; A if take in mind that it is some bland of OSDD and DID elements
DNAngel; B because they do not delve that much into DID/OSDD elements
Rosario+Vampire; A with a twist that I shouldn't spoil
Jubei-chan; A especially for second series
There is also anime where dissociation is portrayed in fusion way.
By fusion I mean two people share feelings and memories like alters.
Gleipnir; A for portrayal of how one can dissociate from other fused person
If you are into anime, I suggest you watch the anime I listed.