Good stories above all: this automatically excludes harems, shounens, games, isekais. Everybody says "but there's this harem/isekai/..." but there isn't*. Changing love interests is not a harem.

No yuri/yaoi and their milder versions. Smut or gore - if I have to. Usually these dominate stories and turn the novel into Xfest, and this really isn't what life is about. 

Good dialogues and or characters are definitely for a plus. Good writing is as well. So is good translation quality.

Overall, a novel needs to have a story to tell. I value my time and have troubles finding it. I'm cooking something
new every chapter is not a story that will enrich me. So is monster of the week. Or face slapping. Face slapping creates enemies and is less refreshing than sneezing or equally short-lasting.  If the action scenes or fights aren't written on a Sapkowski's level, it's usually best to forego them.

* yeah, there definitely will be some 1 in a gazillion exception. But I don't want to read gazillion mediocre attempts at inflating one's ego to find it. I know there are exceptions. The Kingdom's Bloodline uses reincarnation and has traces of cultivation and is overall fascinating. But the weak writers reach for weak tropes and don't even squeeze them, so overall I'm using this as elimination criteria. Aside from reading professional books, historical books and real novels, aside from work and side-jobs, I also live. So - as I said - I value my time.