The shy and sweet ones are my favorites, as long as they don't become the cliché that they are secretly perverted nymphomaniacs, that bores me quite a bit.
Don’t forget: make the game you want, but don’t ignore feedback. Having other perspectives is always good. Try to find a balance between what you like and what your players enjoy.
If it's not a love interest I'm not interested in what they do with the character, if on the contrary it's a LI then I don't want to have anything to do with that character.
As already mentioned, personality is an important point, I personally lean more towards shy LIs but unfortunately most of the time they are not well written.