For years, I've had two recommendations for basic headphones under $200: the Sony MDR-7506 (currently around $80 with a fixed cable) and the Audio-Technica ATH-M50x (currently around $130 with detachable cables). They're both relatively flat and neutral-sounding, something that makes them perfect for musicians and aspiring recording engineers. That trait also makes them excellent for extended listening sessions: the booming bass or exaggerated high end of many other models causes ear fatigue far more than anyone marketing flashy headphones wants to admit.
The Sonys have been around for years, but at some point in the last decade, they changed their ear pads and the best value in audio became one of the most annoying products you could buy. Not only would the stock ear pads slip off repeatedly, it was almost impossible to get them back on. The material that was supposed to slip in the gap and hold the pads in place was just a tiny bit too narrow to keep them on. Why someone at Sony didn't fix this issue is a mystery. Recording studios have been known to buy headphones by the case and these slippy pads have been driving audio pros crazy.
That's a long windup to introduce Dekoni Audio, creators of Earpadz replacement ear pads. Founded by Tal Kocen, the owner of online music retailer Digitaldjgear.com, Dekoni is a product designed to solve a problem and they offer solutions for every budget.
Their ear pads for the Sony MDR-7506 make these headphones the best value out there. They offer Standard ($29.99), Elite Velour ($49.99), Memory Foam pads ($49.99) and Sheepskin ($69.99). All solve the sliding-off problem and all are nicer than the stock ear pads.
For the Audio-Technica ATH-M50x, they offer Standard ($29.99),Velour ($34.99) Elite Velour ($49.99), Memory Foam pads ($49.99), Sheepskin ($69.99). While the M50x ear pads don't slide off, they do wear out and all of these are an upgrade.
If you're working as a pro or wearing headphones for several hours a day, it's worth considering the investment in Sheepskin or Velour pads. If you're a casual listener, the standard pads are really nice.
Dekoni also offers ear pads for higher-end consumer headphones like Beats, Beyerdynamic, Sennheiser, Fostex and AKG
You can find cheap knockoff ear pads buried in the eBay listings if you poke around long enough, but Dekoni is one of the handful of pro audio companies that makes replacement pads that actually improve the experience of using headphones. This is a product for everyone but, if you need them, you really want a pair of these.