I currently have a pair of Koss PortaPros which I love. The sound isn't the greatest, but they are very comfortable and I've gotten used to the booming bass (I am someone who appreciates bass to begin with). Today they broke after one and a half years. Luckily, Koss has an excellent lifetime warranty. These are the longest-lasting headphones/earphones I have ever had. I am not sure why, but my earphones tend to break quickly. One of the reasons why I went with Koss was because of their warranty.
In-ears are very uncomfortable for me, but the PortaPros are terrible to use on the train or in public because too much noise leaks in. However, I plan on keeping them as my casual/cycling headphones because of their comfort and the fact that they do leak enough noise in so I still feel alert.
However, now I would like to supplement them with a full-size closed model. I'm looking at comfort first and foremost because I wear headphones for hours at a time, and portability is secondary because I need to take them with me on my commute. My budget is $150 at most. What's really important also is build quality and warranty quality. I do NOT want to spend $150 on a pair of headphones and have to replace them in 2 years when the warranty expires. Many highly-rated headphones such as the Audio Techinica MTH-50 have a 2-year warranty.
I commute 2 hours one-way (4 hours round trip) every day. On the train and subway things can get especially loud and too much sound leaks through the PortaPros. At home and work I use headphones while sitting on my desk and work. While commuting I use a Sandisk Sansa Clip Zip to hold my music. I do not have nor do I want a portable amp. I may consider one in the future but for now it wouldn't really help me with the leaking issue.
AFAIK Koss is the only company that offers lifetime warranties, but I have not heard good things about their full-size headphones. If anyone could bring other companies to my attention I would really appreciate it. Thanks!