All the different models here have good sound quality, but if you're going to use these earbuds with a phone, I'd suggest going with one of the J6Ms. They're the most updated JBuds - numbered in the same way that iPhone 3 vs iPhone 5 are. If you get a J3M, I can't guarantee the buttons on the mic will work with your device, but on the J6M there should be no problems no matter what device you have.
If you're using them with a computer at home or in a cubicle, you might be better off saving some money and going with a J3M.
If you want to use them for running/exercising, I'd strongly caution against getting the J4Ms. They're heavier and they will not stay in your ears.