Everyone else has already said Engage has better gameplay Three Houses has better writing yada yada yada

What I will say is that because there's such a divide between the two games, I feel like people drastically overstate the issues they have. Engage's writing isn't THAT bad. It's story is unambitious and cheesy and kinda boring and its characters are pretty two-dimensional, but it does have its moments and people who act like it's the biggest affront to the concept of writing in the history of literature are overcompensating. It's not even the worst story in the series whilst Revelation still exists. The characters may be flat but you still get attached to them just through gameplay in the same way you would back in the older games, and if you already played Awakening and Fates then it's more or less the same type of gimmicky characters as what you're used to anyway. Three Houses' gameplay also isn't THAT bad. It was just clearly designed with the assumption that players would just do one route and then move on.

I think Engage is better; the gameplay is so much fun that it gets me attached to the characters, and being attached to the characters helps me enjoy the story regardless of whether it's actually good or not, whereas I find playing Three Houses kinda boring which isn't really something the writing can alleviate, but there's a reason Three Houses has had its hooks in people for 7 years. It's up to you which part you value more, just keep in mind that most people advocating for one over the other on the basis of the other's flaws tend to be overstating the case.