Well, personally, I've had a great experience with the Shure 215-SL, and the MEElectronics A161P.
Believe it or not, the MEElectronics, a lesser known brand I might add, provide a more accurate sound than the Shures, though if you want "Sound enhancement" as in the higher bass, more emphasis on certain aspects of metal music, go with the Shures. For an accurate listening experience, crisp sound, excellent clarity, a selection of tips, and, not to do the bass in these a grave injustice, the A161P bass is very punchy and tight with very good depth and body. It's very pleasing! It is able present proper weight to instruments and voices with convincing texture, and, really, the A161P is a "Neutral" IEM. It will perform well with whatever genre is thrown at it, though, the Shures just seem to have the edge with heavier music. In the end, I recommend either one of these, but give a moderate edge to the A161P.