You know, the first boom that actually grabbed you and pulled you into the story so that you grew to love reading.
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I'll go first. I loved the Harry Potter series with all my heart, were exited for a new book of the series to come out, reread the books a thousand times, read stupid fanfictions and played roleplays online.
BUT the one book that still contains my childhood is 'The neverending story' by Michael Ende.
I still love that one and read it from time to time as an adult.
And I still enjoy it.