Sony MDR-EX71SLA Fontopia Bud Style Headphones
As I mentioned in my review for the EX51-LP, sony's fontopia earbuds are truely are the most comfortable earbuds I've ever used. The sound is great and blocks out externals noises excellently. It comes with soft caps (that insert into your ears) in different sizes, maximizing the fit for anyone's ears. I have the EX51-LP at work, but the original ipod earbuds i use at the gym got crushed and I was forced to replace them. I'd go with nothing less than the fontopias. They are versatile, durable, portable and relatively inexpensive for the level of sound quality.