For romance -straight or BL- I have to like at least one of the leads' visual. Acting matters, but not that much. Facial expression matters, but I can make do without it. Chemistry is expected, but it's fine (well...) even without it. Plot is really important, I hope there's real story instead of only selling sweet nothings and skinships.
For non romance, I want everyone's acting to be good or at least average. Visual doesn't matter at all. Chemistry is super important, it won't do without it. Plot hole is fine, but the whole plot should be at the very least interesting.