I used Sony MDR-V6 (more or less identical predecessor to 7506) for years since the mid 80's. They are good reliable headphones, more or less an industry standard, and provide some isolation. Nice that they fold up relatively compactly for over-ear type closed-back phones. I still have them stored away somewhere although in need of new pads, primarily because all my other over-ears are open-backed.
Headphone preference is a very personal thing. The AKG K701 has too much treble peak for me, for example. Just not a good fit with my ear-canal resonance I suppose. I'm more of a Sennheiser house sound guy. The Mass-drop HD-6XX is what I'd look at if shopping for a replacement for my open-backed Senns today. Have been long curious about Beyer 880 and Hifiman HE-4XX but haven't found the chance to really give them a good listen.
I'm on my second pair of V6's (first got stolen) and I love them for critical monitoring, but don't find them to be overly "pleasant" for recreational listening.
Had a pair of old AKG K44 which I found more pleasant, but a bit less accurate than the V6 sets. One side conked out though and they don't seem easy to repair.
Sony V600 are smaller "on the ear" phones if you don't want as much isolation, I used them in the field for a few years before deciding that I can't monitor in the field with headphones anyhow.
Had a pair of old Sennheiser 414 "on the ear" phones which were a favorite for pleasure listening, although they don't mask outside noises due to the on-ear design.
Lots of folks on the FB group recommended the Sony MDR 7506 so that's what I went with.
I thought 7506 was a V6 with juiced bass for DJs but it looks like it's got less bass in some reviews?