I bought the Spark Plugs after I had misplaced my Plugs (the 1st Koss version), which were very good. I thought that the new updated Plugs would be better, however for me, they weren't as good. The white plastic speaker part is too deep for me, and protudes further out of the ear than the Plugs, which people can live with, and they ARE white, yey. However for me the biggest difference was that Koss had promised a better sound than the old version Plugs, but IMHO (I realise I am no expert), they're very bassy, almost too much so, with not enough treble and mid. You can however, remedy this by adjusting the sound qualities on your generic MP3 player, ie treble boost, which I didn't need to do for the original Plugs.
I suppose what I'm saying is if you're buying something like these for the first time, I'd seriously consider buying the Plugs, rather than the Sparkplug. What properties DO share though are incredible comfort, very light weight, good sound insulation and good bass. I hope this helps.