I have too many favorites to just narrow them down to one single thing. Mine are antiques, retro items(mainly from the 1980's), vintage VHS official releases and home off air TV recordings, action figures, digital media(especially videos that sometimes turn into modern day lost media), older comic books and magazines.
I started collecting things as a kid, and the first thing I loved collecting was fossils. I collected until my early 20's, and I still have that collection today.
Nowadays, I collect VHS tapes, video games (mostly NES since it's my favorite system), and video game paraphernalia like promotional items and toys. I am currently thinning out my VHS and game collections, though, to clear out some space and to make it easier for when I move in the (hopefully) near future.
PLUSHIIIIIEEEEESSSS!!!! I have a plush of Kirby, Yoshi (Orange) Swirlix, a random Giraffe (who I loooovvveee) and also Chunithm Penguin. I also have a figure of Rinka from Pop’n music (when I still liked rhythm games) Someday I’d like a plush of maybe Kaine from Nier Replicant :>
I have another Kirby plush, it is green. I have a huge Kirby plush, and I have Bandana Dee plush \
I primarily collect records, and I will scour stacks of 45s for interesting ones or just ones that catch my eye. I also keep an eye out for out-of-print albums or singles, and I have a few.
My other collection is retro video games, almost exclusively pre-N64.