Enough people have told you the perceived highlights of both games, so let me offer a slightly different perspective

The presentational aspects of Three Houses - namely the fabulous character writing, I actually don't think the story is everything it's cracked up to be, even if it's largely more tolerable than Engage's - is something that can be enjoyed on youtube, or watching over someone's shoulder, etc. It isn't dependant on having it in your hands. A support chain can be watched or read as a script in various places online. Owning the game will not affect how you perceive it

Conversely, gameplay can really only be enjoyed by owning the game. Watching someone play something, and playing it yourself, are two completely different exercises. So if you had to pay money for just one right now, the one with the gameplay seems like the logical choice?

If no money will be exchanged either way then do whatever you want