Voted for 1.2.5 because it's the one I keep going back to, especially for Lyr/Mad Dogs. Perfect combination of bass, mids and overall air. I feel like it CAN be improved upon, but none of the other FW's do it. 1.2.8 lacks both bass and air and tbh, is a little boring. I might prefer it with brighter headphones and/or a brighter amp. For people that are new to the unit, it isn't a bad starting point at all.
1.2.6 I wanted to like, I thought it has the best soundstage of any of them and the detail retrieval was impressive, but was lacking in soul. I might want to try it with tubes or something. I feel like there is something there, but something is needed to "liven" up the music a bit.
1.2.2 is good, but I ended up prefering 1.2.5 in a straight A/B, primarily because of the bass.
1.2.7...yech!