I'll throw some into the ring, along with why I like them, so you can get an idea if they're for you...
Fantasy (I prefer epic fantasy, so if you don't like large, multi-volume series, then these might not be your type):
-The Hobbit/The Lord of the Rings by J.R.R. Tolkien--you may have already read them, but if not, they're pretty much necessary reading for the fantasy genre.
-A Song of Ice and Fire (Game of Thrones) by George R.R. Martin--definitely NOT for kids, so maybe wait on this one, but the world building and characters are top-notch.
-The Stormlight Archive by Brandon Sanderson--another really well-constructed world with unique flora, fauna, and a really cool system of magic. Plus, all of his different series take place in the same universe, so if you like the style of storytelling done by companies like Marvel and Disney, this is a great choice.
-The Wheel of Time by Robert Jordan (last three books finished by Brandon Sanderson): The mythology behind this series is great, and its tone is very reminiscent of LOTR, but there are a LOT of books, and they're all pretty large, so it may take years to get through...even Robert Jordan didn't make it to the end, unfortunately.
-Anything Star Wars, especially books from the newer canon
-Ender's Game--definitely a great novel, and the premise is simple, though the outcome is unexpected. It has some troubling parts, but it's generally viewed as YA science fiction.
-Isaac Asimov also wrote a lot of great sci-fi, mostly in short story form, so if you like quick, one-off tales that get you thinking, I'd recommend him.
As you can see, I prefer fantasy in general, but there's really nowhere bad you can go in either genre, so above all, just go with what catches your eye!