There are some great recommendations in other replies already!

IMO the best YA content right now is actually coming out of Japan (where they’re called Light Novels)

Some series worth checking out:

• Re:Zero - Starting Life in Another World from Zero
• Spice & Wolf
• Ascendance of a Bookworm
• World End - What Will You Do at the End of the World? Are You Busy? Will You Save Us?
• Is It Wrong to Try to Pick Up Girls in a Dungeon?

Don’t let the titles fool you (especially that last one). A silly title will often lead to a deep and complex story only loosely related to the title.

The first three I named are some of my absolute favorites.

And this is just the fantasy stuff. If you’re looking for sci-fi or rom-com, or something a bit heavier/darker, there are plenty more recommendations I can provide :)