W4 has been my favorite IEM for a while despite the arrival of JH13, ES5, K3003 and a lot other high end models. It's neutral yet it has got magical vocals alot other neutral IEMs may lack.
334 has the greatest "WOW" effect when I first listen to them. However, it can get fatigue if you are used to the W4 sound signature simply because its mid-low end happen to be quite in your face and the highs are also more present than on the W4. However, paired with the right source, the 334 can be truly amazing.