I dunno. Over the ear seems like a hassle. I see too many guys adjusting their Beats or whatever in between sets because they're slipping off.
Personally, I don't think it's worth spending good money on earphones for the gym. All that sweat and accidental tugging on the cords will take its toll eventually.
I've had really good luck with Sony Bumpin Buds. They're like $15 at Best Buy. Sometimes they go on sale for less that $10. My last pair lasted about 2 years before the left bud lost connection.
I use mine with a Sandisk Clip MP3 player. Or I connect them to a Jabra Clipper and stream music from my smartphone via bluetooth.