So, you want a pair of closed-back circumaurals. Go over to the Head-Fi forums for an awesome comprehensive list of reviews, but I'll sum up my own opinion for you.
For $150, get a pair of ATH-M50s. You said you've tried them; they do tend to be a bit uncomfortable after wearing them for a while, but their sound is the best you're going to get for virtually ANY closed-back cans under $200. When you tried them, you probably didn't get the best sound they can put out, as it takes a month or so for them to fully burn in and sound their best - both the bass and treble will extend a bit further and the soundstage will widen. Maybe this was already done; if so, never mind.
$200-$300, get a pair of Shure SRH-940's; they're the set I use right now as a replacement for my older M50s. Closed back, velour pads, INCREDIBLE detail and depth. Again, they can tend to be a bit heavy, but I've had them on for 6+ hours at a time with no problems. Velour pads don't get hot and miserable like pleather ones tend to. They're a bit bass-light, but it's to be expected from a neutral set of studio monitors... extension is amazing in both directions. Again, I'd recommend going over to Head-Fi for reviews. A substantial upgrade to the M50s, but for twice the cost.
DO NOT buy anything from Beats or Bose. Sennheiser, Shure, Audio Technica, Grado, Denon, Beyerdynamic all make excellent headphones which sound their price instead of giving you a $10 piece of junk with a $500 name attached to it. Both the M50s and the 940s are also very low impedance, which means you can drive them off of virtually anything, even the smallest MP3 player - the 940s are very, very sensitive. If you plan on spending over $300, I recommending asking over at head-fi about an entire setup, as a dedicated DAC/Amp will help immensely, and the offerings all become a lot more specialized at that point.