Amazing recordings indeed!
The Pogorelich Gaspard is my favorite rendition of this Ravel's masterwork.
In those years the Sebian was a sensation in the classical world and the Chopin thing only made him great publicity.
I also like his atypical, yet highly evocative Scarlatti from the same era... a disc I must have listened to literally a thousand time over the last 30+ years, and it still moves and surprises me anew.
I had the Utopia on loan for a couple of months from a friend (with the Lazuli Nirvana cable btw), and tried the Sol P a few times (although not in my system).
The Valkyria sound signature is
very different from both. Actually I haven’t heard another headphone quite like it.
Both could be considered more technically competent (for instance Utopia wins in terms of resolution, speed, and Solitaire has superior sub-bass response).
However, the Valkyria are - to my ears - more effective than both in recreating the aural and physical feeling of live acoustic performances.
They do this by combining credibility of tone (not the same as neutrality / accuracy), supreme energy delivery, mid-bass density, large yet cohesive imaging, and some other ways that are both long / boring to describe in words and probably very subjective too.
In my opinion they deserve an audition if one is heavily committed to acoustic genres, only caveat being that due to their unconventional tuning they may need a longer adaptation time than usual.