Harry Potter was a good series for the first 3 books in my opinion but then J.K. Started milking the series there is now even a novel set in the universe 19 years later with Harry's son which i believe in completely unnecessary. Yes, the Percy Jackson books may have 5 books in the series but once Percy Jackson's story was done they didn't touch it anymore he is now a supporting character in the Heroes of Olympus
I think both are good but sometimes the way Rick writes is confusing and not clear at all but the Harry Potter books always make you think one guy is the bad but then has a sudden surprise.
In Harry Potter the relationship as friends break apart normally then come back again but in Percy Jackson they need a spell or an real big fight or suspicion
Harry Potter in way more detailed and I can support that because I always have search up the mythical creatures but J.K Rowing describes it so well that the image just comes to my mind.
J.K. Rowling wrote these books with the sole intent of entertainment. These stories were articulated well, and were very thorough and creative.
Honestly, these books should not actually be compared. Harry Potter is based on the stories of the wizard world, while Percy Jackson is based on the world of Greek Gods and other creatures. They're both great stories for their basis.