I really like my RE0s. The bass is very light to be considered neutral, but paired with a cheap FiiO E5 with bass boost on, they are actually amazing. Throw in the fact that the combo is less than $100!
But next to my Westone 3s, no comparison. The Westone 3s are the better IEM. The bass is no comparison. The mids are slightly better on the RE0s and the treble goes to the W3s. Overall, the Westone 3's win for a much better presentation, clarity, and sound stage. They were my favourites until Shure improved on the SE530s with the SE535s.
FWIW, I've also owned: IE8s, ER-4P/S, UE10s and have heard the Monster Coppers/MD, and SM3. I would rank them:
all the rest
Wow, Westone 3 over the SM3's??