Opinion and tweaks on my book idea!?

If i'm honest, the whole 'fallen-angel' idea has been so overdone in literature recently. It's like the number 2. over-done idea after vampires. However, I like your plot. So I think you should tweak it and create a new kind of supernatural creature, not one that has been over-done a billion times before. Find something unique and new that will interest the reader. But please don't join the horde of writers that do fallen-angel love stories, because you'll just be submerged under the masses and your book won't stand out x