I like sandboxes in general, but with a system of built-in hints to let you know what direction to take. And that the grind was within reasonable limits. Of the sandbox games, I really like Bright Past, Club Detention, and High School Days. All of them are in varying degrees of development (Bright Past for example is very close to completion).
Their positive side for me is that they are games, I don't like KNs, it's easier (and more rewarding) to read a book or watch a movie.
As an example of sandboxes that I recommend to avoid:
Ring of Lust:
https://lewdcorner.com/threads/ring-of-lust-version-0-5-5a-votan.3428/
You have to play the game almost blindly, there are no hints, and the probability of getting into a softlock when playing the game on your own is close to 100%. Plus the grind is pointless and merciless, you have to go through the same scene dozens of times - it's just annoying.
There is a very inarticulately written walkthrough, if you follow it carefully, you can get into softlock, but the probability of this outcome is significantly reduced (mainly due to inattentive reading of the game's walkthrough).
There is essentially no plot - after almost 6 years of development, the author clearly doesn't know what to do next (the usual writer's block).
This is an example of how not to make a sandbox game. There are other examples, though not so brutal (Foot of the Mountain, for example, but it is at least barely passable).
But in general, if the developer is sane, sandboxes are able to fascinate, absorb by gameplay so that you lose track of time