The thing to keep in mind about EX primals is that they are largely nothing more than a dance. A few are light exceptions, but for better or worse it just comes down to route memorization. The reason I think most people say that Sophia EX is so far the easiest on release, is that a run is still salvageable even a few people fail mechanics. Take that in comparison to Sephirot EX where, while the amount of memorization is roughly the same (imo), one or two people missing the ball often results in a wipe.