I may have replied to this thread before, but...
Personal preference: SM3>TF10=X10=UM3x
W3 was too weird, only BA earphone I've heard that I didn't like at all. Very detailed, good sized soundstage, excellent imaging, but it was just too colored, too bright, mids were too dry, midbass was just so much louder than everything else.
SM3 takes me to a nice, miniature multi-armature 3D private universe with awesome imaging and no real flaws in the tonal balance or timbre once the filters were out; it was a tad dark and soft sounding for my taste before, but taking the filters out added to the bass impact and opened up the upper midrange and treble. Sibilance comes VERY occasionally since removing filters, but it doesn't outweigh the benefits IMO: more neutral mids, better bass impact, brighter/more neutral overall sig without the veil. The unfiltered SM3 taught me how IEM bass should sound, it only occasionally loses a bit of resolution. Weird/slightly unnatural presentation next to other high end multi-armatures, but has an excellent 3D sound once you get used to it.
TF10 is just a classic. Awesome v shape, very euphoric without noticeably recessed mids, great bass and treble. Colored, but not too terribly much. Good width on the soundstage.
X10 is really warm and colored, but sounds so pleasant, and is just so comfortable and simple to use. If these had a replaceable cable, it would be a no-brainer for a bassy BA at $200. Makes me wonder what it would take to reshell in an ety er4 housing...
UM3x I only had for a short while but it really impressed me with the fully out-of-head sound and great mids. Extension on both ends couldn't match SM3 but the soundstage is bigger overall, easier to figure out, and very technically impressive for an IEM. The dynamics, extension, and fun factor aren't on par with SM3, but I think it is a bit more tonally accurate and very real-sounding.
