Let's see...I have A/Bed the SM3 with the CK10, Copper, MDs, FX700, GR8, e-Q7, and RE252. I owned the IE8, but sent it off just before getting the SM3 and it was lost by the USPS. I owned the TF10 also. I also have auditioned the W3, W2, UM3X, SE530, and ER4P. I am sure there are a few I may have missed, but that is my experience. Technically, IMO, the SM3 is superior. Better transparency, better dynamics, better soundstage width, front-to-back, and top-to-bottom with the best proportions I have heard, better resolution, the ability to change presentation depending on the actual source music meaning they can be mid forward or laid back depending on the recording. Nothing has impressed me like the SM3 has. It has ample bass when called for with a liquid presentation and to me, the most accurate, natural, realistic sounding reproduction I have heard. It sounds more accurate most of the time than my Tesla T1 (although I have not paired it with my new amp for the T1 yet).
Preference does have something to do with it. If you like a laid back sound, the SM3 will not consistently give you that like say the IE8. If you like a forward sound, the SM3 will not consistently give you that like say the SE530. If you like enhanced bass, the FX700 may be best for you. But if you want the best true to the recording reproduction from the IEMs I listed above, the SM3 is it. So much so I sold my others as they all had noticeable weaknesses in comparison to me, making them bothersome (some more than others). I still have the RE252 and CK90Pro as backups, but have not listened to them in quite a while and have no reason to!
There are many good, enjoyable IEMs out there and if you have not heard the others, I am sure most will sound great to you.