I just finished Umineko chapter 3 earlier, so I’ll reply to this before continuing any further in case any of the ideas on which my opinions are based get disproved or complicated in chapter 4.
I like Higurashi and Umineko for somewhat different reasons, so I find it hard to directly compare them. Higurashi is partly something I admire for being creatively cruel with its characters while maintaining a story and mystery intricately linked to their suffering. I’ve been spoiled before on part of Higurashi, and while I do regret encountering it at the wrong time and it definitely isn’t something I’d want to be the one to reveal to someone, that spoiler doesn’t actually dissolve the whole mystery. As a result, I respect Higurashi even more for being deep enough in secrets to stand up to such a blow.
While Umineko does also have its share of brutality, it doesn’t seem to focus on using that to disturb readers. It instead seems to be trying to ask philosophical questions about truth, logic, narrative, and maybe also experience.
I suppose that if I had to choose, I’d say I like Higurashi a bit better at least for now, for its style of creating mystery and for introducing me to the series; however, Umineko is still rich, from my current vantage point at the end of Ep. 3, in mysteries and meta-mysteries, and I feel like I could easily encounter something that changes my preference.
I personally believe at this point, based on what I’ve seen of it, that all of When They Cry can be thought of as a single “unit” in some way, but I have extremely little idea at this point of just what way that is. I suppose that my main “goal” in experiencing these works is to eventually work out not only the meanings of the mysteries, but also the connections between them, and see what kind of beauty the series as a whole presents.