the first one. Percy's adventures are extremely entertaining. I had a few 'isn't this just like Harry Potter' moments (like the trying to recreate a dangerous monster from his remains thing, what's up with that?), but mostly the story is very original. Or as original as you can get when all the adventures are pretty much based on Greek mythology. :-)
In any case, when I read this series I feel like I'm inhaling the story - seriously, these books finish so fast for me, a day or two and they're over! This is strange only because I no longer have that much reading time. Must mean that they're good reads then. And that I have the same taste in books as 9-year-old boys. Ha. :-)
Anyway, these are great fanntasy stories and if you loved Harry Potter then this should definitely be your next stop. Larissa, if you still read this blog, this means you. :-)
Challenges: 2010 Countdown Challenge, What's in a Name?