That is assuming you read
I don't have just one - I read A LOT so I have a bunch of favourites but a few that come to mind
The Alchemist by Paulo Coelho
My Sister's Keeper by Jodi Picoult (yes yes, total sob book and most of her other books suck but I really liked this one)
The life of Pi by Yann Martel
I also really enjoyed the Girl with the Dragon Tattoo and The Girl who played with fire (about to read the last one) but I wouldn't rate as my favourite but definitely among the more enjoyable I have read lately.