Over the years, I had quite a few various in-ear headphones and these seems to be the best so far...
Koss in ear: Sounded pretty good, bass heavy, lasted a week.
Sennheiser CX 300: Decent sound but not great, still works after 4 years.
Klipsh Image S4i: Very good sound, strong bass, too big, constantly tend to fall off, straight jack, lasted 3 moths.
Jays A-Jays Four: Decent sound, similar to CX 300 but not great, good build quality, lasted 1 and 1/2 year.
Sony Sony XBA-1iP: Clear sound, total lack of bass, build quality seemed to be good but I accidentally pulled out the cable in the Y joint after 3 months.
NOCS NS400-101: Great sound, strong bass, light, tiny body, L shaped jack = much more reliable.