Percy Jackson and the Lightning Thief
Why it's similar
Rick Riordan wrote Percy Jackson and the Lightning Thief for his son, and that personal warmth bleeds through every page. Like Harry, Percy is a misfit kid who discovers he has powers and gets whisked away to a place where people like him train together. Camp Half-Blood fills the same role Hogwarts does: it is the first place the hero feels at home. Both books treat their young protagonists with real respect, giving them adult-sized problems (absentee parents, prophecies they never asked for) while keeping the tone funny and fast.
Riordan swaps wands for celestial bronze swords and Greek mythology for British folklore, but the engine is the same. A twelve-year-old nobody realizes the myths are real, picks up a loyal best friend and a sharp-tongued ally, and races toward a confrontation with a villain everyone thought was gone for good. If you tore through Philosopher's Stone because you loved the friendship between Harry, Ron, and Hermione, the Percy-Annabeth-Grover trio scratches that identical itch. I hand this one to every kid who tells me they finished Harry Potter and need more.