My main collection (probably about the same as anime) is wrestling BDs/DVDs.
Most of them are DVD, because A) WWE switched to DVD-only for the majority of their releases (there are only about four/five BDs per year now and they're UK-exclusive, believe it or not) and B) a lot of them are from smaller/local wrestling companies who can only just about to afford to print a few DVDs (but a few of them show off with BDs). Whenever BDs are available, I'll get them.
I've also started getting the standard versions of the Doctor Who "Collection" BDs - partially to replace DVDs I bought years ago (but some of them I never got around to getting on DVD).
I used to collect all the Disney movies, but there were a lot of them (stuff like Aristocats, Pinocchio, Home on the Range, etc), which I was never ever going to watch again, so I got rid of them
I have a fairly sizeable Blu Ray collection largely built on boutique labels like Arrow Video and 88Films. My film collecting mostly slowed down until more recently asides from said labels but with the move to UHD I’ve been building up my collection again with films I’ve never owned on any format.
Like @awadama fever I also collect the Doctor Who The Collection sets, which are upgrades from the DVDs and also favourites within my overall home media library.
I have quite a lot of tokusatsu (mainly kaiju) movies, including all 33 live-action Godzilla movies on blu-ray. I also have loads of Hollywood SF and fantasy, some Disney Classics, and those Marvel and DC superhero movies that the normies like. My Doctor Who collection is mostly on DVD, aside from the newer series, along with 80s cartoons and some other random stuff.
I am a huge 3D movie fan, so I own about 200 3D movie Blu-rays that I watched in my basement "FreyMAX 3D Theater" (my last name "Frey" is pronounced "fry" and not "fray," so FreyMAX rhymes with IMAX) up on my 120" projection screen. I also have 800+ live action Hollywood movies and TV series that I've collected since Blu-rays first came out, but they're now all stored away in boxes in a closet, as I don't watch live action movies anymore. And with the swift death of 3D Blu-rays and the hardware needed to play it on, it won't be very long until I have to box up my 3D movie collection as well, once my current 3D equipment gives up the ghost.
I've also collected about 200 live concert DVDs and Blu-rays, which my one friend and I used to watch all the time whenever he would come over to visit. Since my basement theater system is basically underground, has 6,000 watts of amplifier power, and uses large 15" floor-standing speakers, 18" subwoofers, and Buttkicker shakers under the sofa seats, we would crank the audio up to near-concert levels and be totally immersed in sound, feel, and image watching the concerts on the big screen, without even bothering the neighbors! Unfortunately, my elderly parents moved in with me two years ago, so we can't crank the volume up that much anymore.
For 12 years I hosted Monthly Movie Nights in my basement projection theater to all my friends, neighbors, and relatives, and had a regular crowd of about 15-20 people attend my two monthly showings of a recently-released live action movie on Blu-ray. The last few years I did this I was really finding it hard to pick out even one new movie a month that interested me to show to my guests. I just got so bored of Hollywood movies that were coming out, and once I started collecting anime Blu-rays in 2013, my live action movie purchases slowed to a trickle and eventually ceased altogether. The last live action Blu-ray movie I purchased was back in 2018. I just became much more interested and entertained with watching anime by then.
I actually started showing some anime to my Movie Night guests, who were mainly in their 60s and 70s. I hosted six Studio Ghibli Marathons where we would watch three Ghibli movies back to back on a Sunday afternoon and evening, taking a supper break to eat sandwiches from a local pizza shop between the second and third movies. The older crowd really loved the Studio Ghibli movies. I also hosted a two-night Violet Evergarden Marathon when that series first came out on Netflix. I stopped doing the Monthly Movie Nights altogether after that, and now I just watch anime in the theater with friends an neighbors whenever it suits us.
So I went from barely being able to find 12 live action movie Blu-rays to buy in an entire year, to now buying 12-15 anime series a month!
Why yes, yes I do. I review more than just anime, especially of late, and check discs compete with my own purchases for floor, shelf, shed and attic space in my domicile. I'm still buying DVD it turns out, as some people are still refusing to release hi-def content in hi-def. Recently bought the Episodes boxset on DVD. Poundland has been a drain on my coinage in the last eighteen months, as dropping £2 on a title I've never heard of is no risk, until it becomes an obsession, and given the 20th Century Fox clearout since the Disney purchase, there are some great bargains to be had.
Last year they started a James Bond clearout, and suddenly I'm a 007 collector. Now I'm down to the last few titles I want, and they're only available at around £7-9, and it no longer feels like a bargain, given how much the boxset alone would have been (much cheaper). Still, I won't be compelled to own Dire Another Day, which will be a plus.
I still collect it all, TV series, mainstream movies, niche movies, animation. Since organise my list by disc, and not title, I can see I have around 1700 discs in my collection.
I've got around 2800 anime discs though
Just realised it's probably a lot more than that, as I don't count double dips, but I've still kept the DVDs of films and shows I've subsequently bought on Blu, as back-ups. And the 300 odd discs I've retired with no intention of ever watching again.