I like @generic 's presentation of headphones in order of acquisition. I’m copying.
Audio Technica ATH-2 Circa 1974. I realized that my Veritas were crap. I keep them because I rarely throw things out or sell them. They are one of the earliest of what is now called planar-magnetic. Bass heavy, but so was I back then. Sound nice with a decent amp. Use them for early Led Zeppelin.
STAX SR-5n originally with SRD-6, now use SRM-T1S (modified tube amp). Sorry about talking about the amp, but these are electrostatics. Why? I still love them. They are lightweight, super-fast, and lack only deep bass slam. I got them because they were the best I could afford at the time. Wanted Lambda Pros. They still get substantial use.
Sennheiser HD-580 A friend started introducing me to headphones and tiny mobile amps about 1999-2000. He liked the HD-600s, but I went for the less expensive sibling. Relegated to the home away from home, but I’m keeping them. Nice neutral presentation, and I learned the sound over 20 years of use.
Grado SR-60e Before I got this, I destroyed 2 pair of Sennheiser PX-100s that I really liked. Overuse, trying to wear them while I had a halo for a broken neck, that sort of thing. I’d found this forum, and gave the Grados a try. They made me smile. I still keep them, now with L-pads and the plastic electrical tape pad mod.
Hifiman HE-560 third generation with the wood veneer and 2.5mm cables. In a fit of selfish indulgence, I gifted my better half with some crystalline mineral material, then pointed at a great online sale price near the holiday season. They mysteriously appeared, and I’m very happy with them, as @generic says for similar reasons. These will never be sold.
Sennheiser Massdrop HD-6xx well just because Drop and price. They are much more power hungry than generally advertised.
Grado Reference Series RS1e My most recent headphone, because the friend mentioned above with reference to the HD-580s had a pair of top end Grados for a little while. And since I heard them, I wanted some nice wood Grados. These, the HE-560s, and the HD-6xx are most frequently listened to. They are my EDC semi-portables.
OK, that’s it. Not talking IEM, or things planned in future, or that I can’t find, or broken/lost regrets.