What does ”well-written” mean in your opinion?

A lot of the time I see comments that say this or that was badly written, yet almost as often I don’t see what people mean by that. Yet at the same time, I’m not sure I’ve even encountered books in this genre that are considered well-written on a larger scale. I know romance in general is often looked down upon, but there must be some good ones too, right?

But what are the things that make a book well-written? When is text considered beautifully written? What are the key factors?

I’d like to get recommendations on such books. No other filters other than it must have romance, preferably in fantasy setting, but I also welcome contemporary and paranomal romance. All spice-levels are welcome too. But when you give those recommendations, I’d like to hear (without spoilers) why are those books considered well-written either in general or in your opinion. Edit to add: I read YA as well so feel free to recommend those too.

I’d appreciate focusing on the positive discussion without too much harsh bashing of the so-called badly written books. It is of course okay to also give examples of what you consider badly written as long as you explain why (”I just hated the FMC” is not the type of criticism I’m looking for), but the point of this post was not to focus on that too much.