Before I had the ZX1 frankly the neutral filter was a total fail, I liked the warm for its laid back character and more emphasis on mediums, and used the bright the most for its transparency and shivery (but never hot) treble. I am rather a warmer sound kind of guy so that suprised me. Neutral was kind of a let down for me. I tried it several times but never liked it. I did a lot of source/filter trials. Bright came out on top, with the warm used for late listening sessions for its soothing character. With the ZX1, the warm filter is curiously not as pleasing, the bright is exciting but tiring and the neutral seem to strike the balance I expected from its name. Maybe burn-in is also a factor with 400+ hours now on my SE846.
I guess with different sound sig from sources, filters will have a different expression so to speak. It's a combo, you have to try the filter with your source, I gave neutral a chance with ZX1 even though I had bad experience with it from day one and I don't regret it.