I have the Klipsch X10i and the Westone 3, I know which I prefer but I'll try and describe the differences between the two so you can decide better for yourself.
The X10 is a single balanced armature driver, apparently there is some ported funkyness to pump up the bass,.
I have used the X10i for just over a year, pretty much daily, the good things about them are;
- In line mic and controls, really good (until the buttons stop working reliably), the mic is really good for phone use
- Bass, the bass on the X10i is a lovely fat, shake your ears bass, I had not realised a headphone could do that till I got the X10i
- Definitely not a farting one note bass horror with no discernible midrange like the Beats by and similar lines, play Eminem's "Without Me" and you hear the real bassline, not the confused mess many speakers and phones deliver
- Detail in midrange and treble is pretty good, when the sound is not too complex, very fast and punchy
- Fun and musical sound, relatively forgiving of untidy mixing, vocal and acoustic instruments sound lovely
- Really easy (for me) to get a good seal and fit, really light and easy to wear, put the cable over your ears to kill the horrid microphonics (scratchy sounds from the cable dragging on your clothes), this gets even better with some complys
The bad things about them are;
- Build quality, the cable is falling apart at the connector, just like everyone else's version, if you are in the EU that is OK, you get a 2 year warranty by law so send them back for a repair
- Imaging and separation fall apart when the music gets complex, the initial "wow" of the vocal or acoustic instrument detail, all the instruments collapse into one mixed down smear and the ability to hear where each instrument is disappears
The X10i have served me well for everything from Eurythmics through Nuclear Assault, Beastie Boys through to Warp Brothers, and yes, you stop and listen to the fat bass, then you play it again. The Smashing Pumpkins "Stand Inside Your Love" makes you stop walking just to listen. These are responsible for getting me back into music.
I tried a pair of the Shure SE425 and just couldn't stand them, once I got a good seal the bass was just feeble, vocals were very detailed but missing in weight, male vocal sounded more like female, I tried some Excision and Warp Brothers and there was just nothing there, the last tune I played before sending them back was Puretone picked for the lyric "There's a certain something missing that the treble can't erase" which just summed them up.
These are a 3 way, triple driver balanced armature, I bought a pair at B&H in Manhattan a couple of months back and I have just now got the sound the way I like it. I wouldn't go back to the Klipsch if you paid me (for most music)
Now that I have the fit and sound dialled in, the good;
- Detail the Klipsch can't get close to, midrange and treble fidelity is fantastic (I dealt with the sibilance complaint)
- The detail, fidelity, separation and imaging don't fall apart when the music gets complex, you can easily position each of the drums in Metallica's and Justice for All and you can count the multitrack of Annie Lennox vocals in Who's that girl
- These headphones make me listen to stuff I haven't bothered with for years because it sounds so different now, from the Commitments to Melissa Etheridge
- Sound isolation is great, no microphonics
- Westone make you work for the good sound, it took weeks before the sound was even as good as the Klipsch
- Getting a comfortable and good fit and seal is a gigantic PITA, what Westone were thinking when they put that stupidly short nozzle on the phone I don't know, the only tips that work for me are the long fat comply which are a pain to insert and extract but super comfortable for transatlantic flights (and you can't hear the baby next to you squealing over your unplugged set) and the triple flange Shure tips with the top small flange chopped off but these are nowhere near as comfortable.
- Unless you get the right fit and good seal the bass is just missing, forget it
- The sound is quite sharp and sibilant out of the box, quite hard work to listen to and tiring, I went through this thread http://www.head-fi.org/a/how-to-equalize-your-headphones-a-tutorial and found the huge 6.1kHz resonance in my ears, installed Equaliser on my iPhone and got control of the sound, a sharp cut for the resonance and a nice lifting curve down to the sub bass and all is well
Overall the Westones are fast, punchy, detailed, revealing, they go from acoustic instruments and vocal to thrash metal and dubstep without problem. The bass is not like the Klipsch, it is faster, punchier, tighter, I am sure it is more accurate but it is not as much fun. I fear I may be a dynamic driver bass person... The bass is all there in the Westone down to 20Hz without issue but it just doesn't have that enthusiatic flapping big driver cone sound which works for some music, seems lacking in a little liquidity too. The percussion on "and justice for all" is like I have never heard it before but beware, they don't forgive loose sutdio work, "Stand inside your love" just doesn't quite gel when it doesn't get mushed down into a wall of sound like the Klipsch, "Porcelina of the vast oceans" on the other hand is delivered with a mix of subtlety and aggression I hadn't realised one device could deliver before.
I suggest you do the eq curve for whatever you buy, for my money, I'd spend it again on the W3 over the Klipsch without hesitating, for all the problems getting the sound once you have it there is not really any comparison.
Hope that helps.