Still playing Gakuen Idolmaster in fits and starts. While I don't think I've seen absolutely 100% of what the main character raising loop offers in terms of systems and mechanics, I do feel Uma Musume ultimately has it beat in terms of both strategic depth and making that depth intuitive and accessible. Gakumas, as it's abbreviated here in Japan, is definitely a neat spin on the fundamental formula, especially with its deck building component, but there's just a smidge too many passive buffs and whatnot to keep track of during lessons and exam sessions for my liking. Not an unmanageable amount, but enough to still bog down my thinking process a lot of turns. Some of this will probably diminish with time if I stick to it more, but I just think that the way Uma Musume's stats play off one another and especially how they manifest in very tangible ways during races is just hard to beat. In this game's defense, Uma Musume's setting is a big reason why those mechanics are even feasible in the first place, but it does mean that the raising loops is "merely" very solid, but not necessarily engrossing on its own merits for me.
But the character writing and story cutscenes I've seen so far? Very excellent. The cast is fun and has great chemistry together and making it take place in a school for both idols and producers, with your character being the latter leads to some dynamics that the series hasn't quite had with its usual adult producers. And as for the animation and facial expressions? THOSE are where this game arguably shines it's brightest. Idolmaster has always been an excellent showcase for how to apply motion capture in fun, vivacious ways that you just don't see in other games and Gakumas' characters are just captivating to watch move around, even in regular cutscenes, where they'll often shift poses in significant ways mid-dialogue. It goes a long, long way to giving these characters warmth and in that regard, I'd say it gives Uma Musume a run for its money, and that game is no slouch in its animations and direction, either!
I get the impression this game is under a region lock at the moment without a VPN or something, but if you want what's probably the best character raising sim released since Uma Musume, then look no further. It might not take the crown overall, but it is incredibly well made for what it is and clearly not a game that they made on the cheap.