I always want more detail in the world-building. I want magic systems with rules that make sense, magical creatures with weird biological limitations like regular animals. I want magic that’s more like coding or engineering, isn’t just off or on but doesn’t work properly all the time or has to be debugged. Sanderson’s Mistborn is a good example of a magic system with clear rules. Related to world-building: more interesting settings. Future, past, completely different universe, make stuff up, but there’s just too much that’s thinly veiled ‘medieval europe’ vibes and that gets so boring. I also want less chosen-one magic in fantasy. One of my least favourite tropes is a chosen one who can inexplicably do the most powerful magic or speak a particular language without knowing it (that’s not at all how language works!). I want my protagonists to fail, not epically and tragically but just normal everyday failures and imperfections.