I don't feel I should venture into this party, but I'm here now so here goes:
TLRs:
Late model Rolleiflex 3.5f which is my main user. It has replaced an old Rolleiflex Automat which replaced several flavours of Minolta Autocords (still my favourites) and YashicaMats. I've also got a semi-functioning Art Deco Rolleicord and an old Lubitel which came with film in it but I haven't been able to figure out what it is. I have a beautiful Voightlander coffee can TLR as well, but it's not intuitive to shoot with and the old lenses are very soft and have the most incredible flair, which would be interesting with the right subjects, but not for everyday shooting. At the moment I've got 11 TLRs sitting in my camera case but I know I have more back in Canada. Most of them are working, or kind of working, but I don't use most of them anymore because of various issues - light leaks, image spacing, skipping frames, sticky shutters, etc. It always seems cheaper to buy a "new" camera than service the old one, as in my experience one problem may be fixed but they come back with a new one.
Holgas and pinholes:
My main user is still the first one that I bought over 15 years ago, a Holga FN, although I have never used the flash or keep batteries in it. I like the vingetting on this one more than any others. I have about 8-10 Holgas, including one with a glass lens (which sucks) and the Holga wide pinhole version. Mostly I have so many because I bought a few as backups when I found out the original Holga factory was shut down and the machinery destroyed.
As for pinholes, I have a couple from Reality So Subtle - a 6x17, and 6x6 (filter version), and the 6x6 knock-off from Ondu. I have a very battered Pinhole Blender as well, which I still like shooting with, but doesn't get as much love as it should.
Systems:
Bronica SQAi which replaced the Bronica SQA I originally bought. I originally bought this because I wanted the multiple backs and lenses to give me more options than a TLR. However, over the years I kept paring back what I brought with me for travel until I just had one lens and one back, effectively making it like a TLR. I have some good lenses and backs and multiple accessories for this (honestly, it was my main user for nearly 10 years) but I can't even remember the last time I used it. I should probably put it through its paces to see if I want to keep it, or just get rid of it. I'm loath to get rid of gear I love but don't use, in the event that I ever want them back, but the reality is I don't have the room for all these cameras so it probably makes sense on multiple levels to just let it go.
Mamiya 6MF - bought to replace the Bronica since I wanted a lighter system but with excellent quality. At the time I had a lot of back issues so I thought this would help me. However, the meter is unreliable in bright light and I'm not a fan of rangefinder shooting or the lack of close focusing. I should probably give it another chance and if I still don't like it, will sell it.
Eventually, after years of shooting with the Bronica and the Mamiya I went back to TLRs (the Rolleiflex right now) because it is simple, lightweight and easy to use. So, long story short, on a regular basis, for MF I'm using the Rolleiflex, Holga, and every now then, pinholes.