If you want a bright sound signature with insane clarity, I would recommend the UM3X. They are a little cold sounding, though. They have remarkable bass (it's very kicky). The IEM is also very sparkly, but a tad analytical. When you listen, you appreciate sonic quality instead of feeling like you want to dance. The separation is simply unparalleled. They are magical for electronic music because of the sharpness.
For a dark sound signature, I would recommend the SM3s. It's an all around great performer with good mids and lows and exceptional soundstaging. The bass isn't very tight, but is commendable. Its major weakness is highs. Treble is not sparkly or super clear, and so the image isn't as sharp across the entire spectrum. It's definitely more fun than the UM3Xs and simply different. It has a very solid and thick sound. I would describe the SM3s very good generalists, but a master of none (which, actually, is a good thing in most cases concerning headphones). They're pretty good at playing most types of music, but not for things with really intricate and delicate sounds. I would imagine they are pretty good for rock, for example, but I have absolutely 0 rock songs, so I wouldn't be able to attest.
If you really like female vocals, very vocal centric music and upper mids, then the SE535s are really the masters there. It's honestly their specialty and vocals that inhabit the upper mid region are simply stellar. They are so remarkably clear and incredibly intimate; it's like they're singing in your ear. 535s are bass anemic and really focus on upper mids and try to push treble. As a result, lows are kind of lacking, but lows aren't too important for some genres of music. The overall clarity is greater than the SM3s though. For example, Hayley Westenra sounds magnificent on the SE535s, and the clarity and closeness of her voice is just unbelievable.
