Go to Head-fi.org/f/
. They know what they're talking about.
If you are looking for soundstage, you are looking for an "open" pair of headphones. This does a lot of good things for sound quality, but provides absolutely no sound isolation. It's more like putting small speakers close to your ears than headphones. People around you can hear what you're listening to, and you can hear them. Just be aware of that. Knowing that you want "open" cans and have a $200 budget, figuring out what to buy isn't too hard.
I am typing this from between the velour cups of the Sennheiser HD 598s. I got them used for well under $200. If used isn't your thing, try the HD 558s (a minor step down for a significant price drop), also by Sennheiser. They're virtually identical to the 598s. Other options are the Audio Technica AD700s at a significantly lower price point ($100 street, lower used). Pretty much universally agreed to be worth far more than that, especially for soundstage. Also acclaimed for being comfortable. The bass isn't immense (which is the case for most open headphones). Unfortunately the headband kinda messes with a person's hairdo (unless you have a fauxhawk or something), which matters to a lot of people. Those options probably give you the biggest bang for your buck as far as soundstage/comfort go. "Sound quality" goes up more linearly as price point increases, though diminishing returns really hit right above your price point.
Buy used if you can; Head-fi has a classifieds site. That's where I got my 598s. Ebay is way overpriced.