Sorry to make such a similar post to the $30 one, but I want to be able to use these things all day and not get mad at them. So comfort is a plus. I like isolation, and I don't want a mic on them (unless it'll be better than my desktop mic)
I do all three pretty regularly. Gaming's probably my biggest thing, but I don't want a microphone because I'd like to use them for walking around music, unless it's detachable. Folding up would be a nifty feature.
For under $100 yo have the Sennheiser HD 280 PRO - very good, a bit heavy. EH350 lighter and on-ear. I think you should get the Denon, light and great value for the money, they compete against $300 headphones.