The Harry Potter book series is the better by a long shot. Harry potter and Percy Jackson are both very good book series but Harry Potter is better for 3 reasons.
#1. Harry potter has more realistic Characters. Harry potters characters were written beautifully to be as realistic as possible all the main characters have faults, Strengths and emotions. Percy Jackson's characters often times do not have these traits. Take Neville Longbottom for example Nevilles parents are permanently stuck at Saint Mungo's Hospital after losing their minds after being tortured by Bellatrix. The pain of this loss stays with Neville his entire life.
#2. Harry Potter evolves as a series. One aspect I've always enjoyed about the Harry Potter series is how the books evolve over time. Take books 1-3 for example. The First 3 books are more light-hearted and family friendly than books 4-7. The books steadily become more intense and heavy as you continue exploring topics such as death of someone close to you and to an extent PTSD (I'm talking about Cedric Diggorrys death at the end of the 4th book) This aspect of the books is very cool because the books grow with Harry's in-book progression into adulthood and the heaviness of it
#3 Harry potters plot is handled with the grace of an experienced author. Despite the fact that Harry Potter and Percy Jackson have very similar plots J. K Rowling was able to handle the plot of "Prophesy About Boy Forces Him to Fight Super Powerful Bad Guy" in a way the Rick Riordan could not despite the fact Harry Potter was her first full book while Rick had written a fairly successful book right before. With the Percy Jackson series the big confrontation between Percy and the half-bloods and Kronos and his army felt forced and rushed whereas with Harry Potter J. K took her time and let the events fall into place slowly and delicately letting the final confrontation happen in a fairly natural way.
Those are my 3 reasons why Harry Potter is better than Percy Jackson
I simply like how rich the storyline of Harry Potter is. Although Percy Jackson may be newer, I prefer how the Harry Potter books have captured the eyes of many generations, And will hopefully continue to in the future. My personal favorite book is the Prisoner of Azkaban. It is also just as intense as Percy Jackson, With the deaths of multiple major characters. I’ll try to avoid spoilers, But my heart sank after the Order of the Phoenix
In Percy Jackson, They have actual information, And while reading the books I leant lots about Greek Mythology. I do like Harry Potter, But Percy Jackson is better.
Also, Is it just me or are these books really alike? A prophecy containing the main character, Two supporting characters, One male, One female, And many more.
They are more intense and have more fun. Harry Potter's had its day. I do like HP, But PJO makes things a lot better. Sure, Somebody might say that PJO is a kids' book series, But how are deaths, Emotional and physical pain, Violence and more a kids' book series? I guess it might be for some really mature kids, But PJO is the one to go.