Yay! Fun topic, I have a few different sets I listen to on a regular basis:
IEMs - Phonak PFE's -
http://www.audeoworld.com/en/US/default.htm - I would highly recommend these for anyone who wants a fairly neutral sound, they can be customized using filters that come with them to suit your personal taste. I'd say the biggest limitation with these is imaging, which is a weak spot for just about every IEM and most earphones in general.
CANS - Grado SR325i's -
http://www.gradolabs.com/page_headph...7da233d0238ccd - Kind of a cool retro look to them, I really dig the look, these are pretty in-your-face sounding can, great for rock and accoustic. The big drawbacks are a lack of bass and the fact that they are an open design so that you really can't use them well in a loud environment, and they don't isolate others from your music either, my wife yells at me all the time to turn them down.
CANS - Ultrasone HFI 780 -
http://www.ultrasone.com/index.php/e...s/hfi-780.html - I bought these as a backup for my Grado's as they isolate, and also I was craving something with a bit more bass. These quickly became my go-to earphones, they can handle pretty much anything you throw at them, they have a lot of bass, and decent isolation so I can turn them up in my office without worrying about disrupting all my co-workers 3 doors down the hallway. I'd say the biggest weakness to these is heat buildup, I can't where them too long or I feel like I am wearing earmuffs in a sauna.
A good resource for headphones is
www.head-fi.org, but be warned, they have a motto "Welcome to Head-Fi, sorry for your wallet". It can be a fairly expensive hobby if you go down the rabbit hole.