I have yuin pk1, blox tm7, sunrise as-charms, pk3s, mx580s, mx760s.
Frankly TM7 is the best of the best when it comes to sound, but its slightly larger than the yuin buds which makes it not as comfortable. If you owned the m2cs then its the same housing as TM7. I highly recommend blox, and i believe the m2cs are available now on their site, but I have not heard them to compare them to others. Although, they have been getting great praise from people here at head-fi.
The TM7s are not being sold at blox now.
I feel like you can't go wrong with the yuins because they are really comfy, and sound great out of the box. The pk1s are very fun and sound very good, but you NEED an amp, if you dont have one, then its not worth having them really. I can't speak for the pk2s, but I enjoyed the pk3s, so I'm sure the pk2s can hold their ground.
You can check out this thread: http://www.head-fi.org/t/441400/earbuds-round-up