Professional users have very specific requirements and their preferences shouldn't be taken as a general recommendation.
For years, we used the Beyerdynamic DT-100s, which sounded absolutely awful but suited a professional environment well. They were ultra-rugged, provided good isolation from outside noise, were completely rebuildable with 100% parts availability, had a modular cable and provided a good reference in the mid-range frequencies which are most critical for broadcast. You'd never mix a record using them, but they were excellent for musicians or cameramen to monitor with. Similar logic applies to speakers like the Yamaha NS-10 or the Auratone 5C - horrible to listen to, but they provided a useful reference for specific tasks.
The MDR-7506/7509 headphones are very popular for similar reasons to the DT-100s, although they sound much better. Here in the UK they're not especially popular in music, though they are used extensively in broadcast. Open-backed headphones like the AKG K701 or the Sennheiser HD650 sound very much better, but they're bulky, fragile, don't block out noise and leak sound out, which is a critical failure if you're sat in front of an open microphone.
The Sennheiser DT-25s are another example - probably >50% of DJs use them, but they'd be a terrible choice for most users. They sound good, are very rugged and provide superlative isolation from noise, but they're miserably uncomfortable. DJs are quite happy to trade comfort for isolation as they only use their headphones intermittently, but for users who aren't trying to monitor in a noisy nightclub it's a bad call.
There's little point in spending more than a few hundred dollars on headphones, but they're very specialised tools and you should select carefully based on your personal requirements.