All 3 buds I've owned in the past (2 Sony PSP buds and 1 pair of standard iPod buds) have died in about a year due to chordyanking f'ing up the wiring to one of the speakers. I'm using some Senheiser ones right now that were under 15 bucks, cheaper than the ones that advertised better bass. Didn't want to risk too much money on an unknown.
Overall the Sony PSP ones were the best I've owned. The bass came through very clear and dimensional, and everything sounded perfectly balanced and dynamic. I'm not sure if the sound is the same on any of the newer ones, all I saw at the store were cheap 10-12$ ones with annoying over-the-ear holders.
The iPod pack-in earbuds are just fucking dismal. It's like everything is compressed into a muddy crapstream. I weap for the millions of people who own those and think that's what music is supposed to sound like.
The Senheisers are damn good, but just a touch under the Sonys in terms of complete sounding frequency range. They do high and mid range very nicely, though. Their biggest advantage is the superior design, with L-shaped jack and reinforced chords going into the buds. I have a feeling they will be more resistant to chordyank down the line. Another significant advantage is that they seem to have more power, I notice I have to turn the volume up much less than with the iPod packin buds to listen comfortably. It's been to long since my PSPs died, so I can't compare them on that front.
The price is right, so I'll have to give these Monoprice ones a try, just to have a spare pair.