Previously
Technics RP-DJ1200: ~1997-2004. Kind of stupid DJ headphones, but I liked them at the time. Lots of bass and you could swivel one earcup independently so yeah, that was a feature...
Alessandro MS-2: ~2004. I think I only tried these for a few hours, couple of days at most. All I remember is they sounded awful and I didn't like them at all.
Sennheiser PXC 300: Active noise cancelling from the late 90's/early 00's. Took two AAA batteries in a nice hefty battery pack someone along the cable. The ANC definitely did 'something' if you were on a plane. I don't remember anything else about these, so not sure musical enjoyment ever factored in. Foldable too I see... cool.
Sennheiser HD25-2 II: ~2010-201?. Never liked the split headband, but these were fine. I can't remember anything outstandingly good or bad, sound or comfort-wise. I sold them in the end because I decided IEM's were easier for travel, which is what I mainly used them for. Sometimes feel like giving up and just getting these again for everything.
Audio-Technica ATH-A900: ~2007-2015. Loved these for the entire time I owned them until I got the TH-X00's and then realized I'd been listening to the inside of two tin cans for eight years. Supremely comfortable though.
Fostex TH-X00: 2015-2020. I enjoyed these (hence five years), but in the end felt like everything was a bit soupy with some tracks presenting some horrible treble peaks or something like that. Fatiguing and aggressive in that respect. The stock pads weren't very comfortable either - Yaxi Alcantara were much better. I did the Lawton DIY mod, but didn't find it helped much, if at all. The massive heavy cable was the final irritation, after switching from a desktop to laptop setup.
64 Audio U12t: 2020. I had these for a couple of months. Easily the best thing I'd ever heard and I thought I was done for a minute. However, practical issues defeated them. I don't sit for long enough to be able to deal with IEM's that need to be put in just right, cable looped over the top of the ear, seals created, etc. I find I'm up every few minutes to get the door, let a cat in, let a cat out, let a cat come halfway in and just stand in the doorway preparing to be instantly displeased with whichever option it picks, make coffe, make tea, eat stupid lunch... And because they sealed, as IEM's do, I can't hear anything else. So the doorbell is registered by my wife throwing desk detritus at me because she's on a Zoom meeting. If she speaks I have to notice, pause whatever is playing, pull an ear out, ask her what's up, and generally get a sigh "NOTHING!" in response by the time I've done all that. All of which to say, I became aware of how important considerations around ultimate sound quality are with this stuff. I also tried to Bluetoothify them with Fiio UTSW1's, which were intensely uncomfortable, introduced BT lag, and possibly damaged the connectors in one unit prompting a warranty repair. Disaster really, but they did sound good.
Focal Elegia: 2020. Just returned these after a few weeks of use. They are good, but I just wasn't enjoying them. I tried adding a Hidizs S8 which made them much better than the laptop headphone socket (big surprise), but still no fun. I'm not sure whether Crinacle's summary of "Severe lack of upper midrange and treble results in a muffled, dulled tone." is right, or whether it just got in my head so that is what I heard, but either way I agree. I got them in an Adorama $400 deal, so was thinking are these good for $400? If I paid $900 for them I don't think I would have given them as long as I did.
Current
Etymotic hf3: Had these since ~2013. Only good for phone calls these days. They sound fine when out and about, but comparing with anything else I have to hand and it's not good.
Etymotic ER4XR: Bought Nov 2020. I guess like the hf3's but with extra bass, less ear-assaulting highs, and more detail. Better tone and less fatiguing all round.
Incoming
Hifiman Ananda: Just ordered. I have never once tried open backs. Or planars.
I've got Focal Clears on the watchlist, but can't deal with full price when they go on sale for $899, so they can wait. I was thinking about E-MU Teak's as well, since the TH-X00's were good, but am concerned they'll be too similar - soupy and uncomfortable. I read somewhere they don't do as well with pad swaps either, so the comfort seems to be non-improvable.