i have both the UM1 and the X3
if your going for comfort and budget is not a problem, by all means, go fr the UM1, i've heard rave reviews abt the comfort level of UM1 and i wasn't disappointed one bit. other then the occasional thug frm the wires when your walking. i couldn't recall plugging into a pair of IEMs. though some ppl may not like it as it covers the whole of the ear. its isolation is very good.
the X3 gives me a cheap and flimsy feel. however, the strong bass, cheap pricing and reasonable sound quality makes up for it.
ratings for um1
build : 7/10(transparent looks damn 80s)
comfort : 9/10(if you dont mind it covering the whole of your ear)
SQ : 8/10
ratings for x3
build : 6/10(flimsy rubberized material)
comfort : 7/10(if you like the airy feel around the ears, u'll like it)
SQ : 7.5/10