The Last Kids on Earth is a favorite of my 10 year old, he started reading them at around 8- we read those aloud and my older son likes to listen too. The Diary of a Wimpy Kid series my oldest ready from 3rd to 6th grade and still picks them up occasionally, same with Patterson’s Middle School series. Those are both funny. My now ten year old is really athletic, and he likes the Junior Ninja Champion series too. Also if you haven’t read it- Wonder is not a series, but it is so good. My kids were 9 and 6 or 10 and 7 (can’t exactly remember) the first time we read that together, they both loved it. We’ve read it several times since then too. (If you do read this one, be careful with the second book. My older son and I read that one together, and there’s this whole thing about the Holocaust in there, which my son knew nothing about up until that point. He was not ready to hear that, especially right before bedtime. That was a very long night with a lot of questions. But the first book is fine, and they’re both very good. ) For your older one (and maybe your 8 year old) Gordon Korman is great. My oldest is almost 13 now, and we read Korman’s Restart together a couple years ago, and it’s still on his “favorites” list. Restart is his favorite of Korman’s so far, but he’s read a bunch of his books and liked them all.