Since we have a thread like this in the full-size forum, I've decided to start one in the portable forum as well. The below is based on what olor1n posted in his thread.
If you're new to Head-Fi and are seeking advice, hopefully this thread will assist you in making an informed decision.
Head-Fiers are generally happy to help and can draw on a wealth of experience to shed light on a question. All you need to do is give us some context, so please outline some parameters like budget, music preferences, open or closed design, amped or unamped etc. Help us, to help you!
If this thread serves its intended purpose (and I encourage all members to help in this by referring people here), it should inform future members who'll no doubt formulate the same questions. So ask away.
Oh, and welcome to Head-Fi. Sorry about your wallet.
Note that this thread is for portable and in-ear headphones (buds, IEMs). Don't forget there is a forum for full-sized headphones with a similar thread.
Also, please read the last few pages before posting. Searching the site at large can yield strange results but try searching THIS THREAD with relevant terms like genre and price. It's likely an answer posted to a similar question may set you on the right path.
Some useful links: