Been meaning to do this for awhile...let's consider this a "working" list that will undoubtedly change over time.
Note, I have the 64A Nio incoming, I am selling my Valk and Tux 5, and I am considering strongly swapping out my EE LX for the LX SE. The addition of the Nio and potential swap of the Legend X's could change the below...
All-BAs:
1) 64A U12t: a more capable version of the Andromeda Golds across the board; in particular, a much wider stage, deeper lows, and better clarity/instrument separation; of the IEMs currently active in my collection, these are the most neutral (and that alone gives you a sense of my preferred tuning) and analytical.
From a price/value perspective, I'm not sure I would choose the U12t's over the AGs comparing MSRPs (let's say $2000 vs. $1300), but I got my U12t at 20% off, and so that gap ($300) vs the AGs made the U12t a worthy upgrade
2) CA Andromeda Gold: loved these guys...punched well above their weight, excellent warmth, nice mids, super clear and sparkly highs
3) QDC Anole VX: overall I found these to be quite capable, but nothing stood out to me...almost a "boring" tuning with all the switches off; this is most likely reflective of my personal tuning preferences; when I fiddled with the tuning switches on the VX, each change would improve one aspect of the FR, but detract from another (i.e., a zero sum game); for example, when I turned the bass switch on, I found the VX bass to be better than the U12 bass - hit deeper and fuller - but I thought it bled into the mids and found the treble to also lose the clarity and sparkle I heard with all the tuning switches off...so, bass significantly improved, but mids and highs were worse in exchange; so at the end of the day, these are great and highly capable/technical IEMs, but I almost came away from them thinking, "meh" - nothing inherently special that stood out to me. I was a/b them vs the U12t and the U12 is so much clearly the better IEM for my tastes and preferences across the board
Hybrids:
1) Solaris 2020/EE LX: I am still undecided about which I prefer. The LX obviously has the better dynamics, but the Solaris has a wider soundstage, better holographics, and better overall balance. I don't find the differences otherwise to be better or worse on one vs the other. For example, the 2020 also very clearly has better defined mids, but the LX' mids don't bother me, per se (i.e., many describe the LX as a "L" shape sig...I don't see it that way - I think the LX is an immensely capable and technically adept IEM across the entire FR). Either could be my daily go-to. I'll make a decision soon so I don't feel like I'm "cheating" by not making a clear decision here.
2) Solaris SE: just a small notch below the 2020; I found the 2020s to hit slightly deeper and harder with bass (which I like), and also have a bit more sparkle with upper mids. Outside of sound sig, the fit is also much better (although the SE's fit didn't bother me...the 2020 still has a better fit).
3) EE Valk: I LOVE the juxtaposition of the estat and the W9. Definitely a V-shape, but it's done very very well IMHO. The treble is super sparkly and forward, yet without even a hint of sibilance. Only reason I'm selling is because, regardless of how much I love them, I find myself reaching for the U12t, the 2020, and/or the LX over the Valks...I guess I'm hitting the ceiling in terms of number of IEMs I can practically have in my collection. But - I don't have anything bad to say about these beautiful IEMs.
4) Noble Tux 5: much like the Valks, these would not be for sale if I hadn't had the fortune to try the other IEMs in my collection; the tuning of these is very much in sync with my preferences (warm), but I would just never reach for them over the 2020 or the LX, and so I struggle with the rationale to keep them. Excellent dynamics (just a touch below the LX in quantity, and just a notch or two below the 2020 in terms of quality); slightly recessed mids, but overall very good; excellent highs, nice and clear, no sibilance; the soundstage on these is wide, but nowhere near the width of the hybrids above - this is probably the one aspect of the sound sig that is most lacking
5) 64A Fourte Noir: many of you may think I'm crazy to put these last, but there's one very clear reason for this - the treble was much too hot for me. Too hot, too peaky, too sibilant. I'm probably a bit sensitive when it comes to treble, but I had so much of a problem with these that I honestly just couldn't listen to them...so I had to part ways with them. Outside of the hot treble, these are super super capable - amazing dynamics (nearly on par with the LX in terms of quantity and much tighter/higher quality); mids were amazing, nice and forward; stage super super wide - depending on the track, on par or better than the 2020/SE. So, there are amazing in so many ways, but the hot/sibilant treble made this a deal breaker