Here are my main collections:
I collect Brave because it reminds me of my mother and myself. I mainly collect Elinor and Merida pins for this reason, and I'm still missing two of them haha. I do love the movie though so any other really nice pins that go with the series look great to me. There are some that I can do without, however (the new Easter egg pin is just eh for me, I decided).
I collect Mulan and Fa Zhou because it reminds me of my late father and myself, or rather, what we could have been! Fortunately there are only four pins of the two solitary figures together, and I have 3/4. Hopefully I can consider myself a completist of this collection soon!
I collect Stitch because he is cute and fluffy (and slightly evil at times). I would love to complete certain sets of Stitch, such as the Stitch Invasion series of him in other movies, or him with other characters period. Those are my favorite pins. Stitch pins make me laugh, which is really fun to me, and makes me love them. But some I think are just plain hideous and I would never add them to my collection!
I collect Gaston because, well, I just love the man to pieces. I prefer pins of him as a single character, but I also like ones of him with Beast (like the 110th Legacy collection). I will never consider myself a Gaston completist, because I can't see myself making the effort to get all of the pins, ever. I have higher priorities!
I collect Pocahontas as much as I can, but unfortunately her harder pins are REALLY, REALLY hard (way more than I originally thought), but she is my favorite princess (well, tied with Merida). I would like to be a Pocahontas completist, but I have barely even started to even attempt to call myself that haha.
I collect orange kitties because of my precious kitties who are no longer with me. I also would not consider myself a completist of these either. I just get them as I can for my display, as memorial tokens
Some I like more than others for sure though!
And I collect princesses when they are pretty, plain and simple. I think its rather impossible to consider oneself a completist for princesses haha. However I WOULD like to complete the princess Beloved Tales series...though I find this to be rather unlikely haha