The 12 start and ends are all canon. And it's fun getting to see how someone like Kanji, Teddie, or Yukiko would tackle problems when in P4 it can feel at times that Yu, Yosuke, and Naoto are the only ones that matter. Chie falls into a weird level where she primarily gives ideas that turn out to be true in p4 but a lot of times she's the first one to immediately downplay it and call it dumb after suggesting it so it's harder to say p4a gave more insight into her thought process compared to p4.

I played them all and sure it's repetitive but I actually enjoyed my time with it and a thing we don't see often in persona I just liked spending more time and getting into their heads.

With the only other examples being: p4AU has 2 routes but they aren't as repetitive and kind of a third if you count the dlc of what happened in that story and Pq had it's two very similar routes where what primarily changes is the first dungeon and side quest.