I’m going to take this as, like, a favourite cover theme. So, for me it would be very simplistic covers!
Here’s 10 simplistic covers (has what the book is about on the cover or a basic symbol/colour theme) that I’ve really loved:
I also very much recommend every single one of the books above! They’re really quite amazing. If you need any trigger/content warnings or want to know about them, feel free to send me a comment/ask about it!