This is a list of MY OPINION of best books, so don't judge. Also, most of them are appropriate for 8-12-ish, except for the Infernal Devices, which is probably around 11+, depending on if you think you're mature enough and if your parents let you. Comment if you agree/disagree.
I'm assuming the Candymakers is a trilogy because the sequel ends in a cliffhanger. But a third book hasn't been confirmed yet.