For me, Harem is one of my favourite genres. Harem can be done wrong or it can be done right. To make the MC and the girls have personality is the most important thing possible! In JP anime (monster Masamune) it is legit fucked up with the point of being unwatchable with my preference. It has a story, but it never shows why the girls love him so much. There is only one explanation: He is a girl magnet. WTF?
I hate JP harems because they never truly try to make you understand what good and what bad qualities a person has. The writer will be lazy and say something like: He is a good person, high morals and quite intelligent. But the question is, the people those protagonists flirt with are all high ranking members of society! They have everything. Why did the fall for this stupid piece of crap protagonist?
The way to do a harem is to build foundations for the Female harem members. I think My Wife is a Beautiful Ceo does that quite well. They should all have at least an actual reason to find the protagonist interesting instead of: Yeh, he is a good persona and has nice looks.
Harems can be fudged over too easily like this. I won't say that the book I have written has done what I said. It is harder to put the knowledge into context.
So, if you want a harem. You will be fucked in every way possible... I have nearly never seen a harem story that stays well until the end. The Divine Throne of Primordial blood had a harem but the poor guy had to abandon it because his main Female Lead nearly went crazy because of it.
The conclusion is: If you want to be fucked, then go with a harem. If you want a story that will not have a stupid plot and be a bit serious, then go without a harem.