Is 'The Alchemist' best book you have read ?

About the opposite.

I'm not going to say that it's the worst book I've ever read but I didn't think it was awesome.
What I will say is that it was an easy read, it was even kind of entertaining but the conversations, the ostensibly deep spiritual truths that the story tries to convey sounded like Captain Obvious style drivel to me. And of course, the point of the book wasn't what I'm normally looking for in fiction, which is a good story, but rather to convey these "truths" which is why it ultimately fell flat for me. The denouement at the end was just as shallow as the pseudo-philosophical talks the main character had along his journey.

Given its popularity I realize that the story scratches an itch for many people, but I'm not one of them.

No. It wasn't even the best book I'd read that day. 

No the best chemistry book I've read is 'Facts, Patterns and Principles'

They Shoot Canoes Don't They is my best . 

Not even in my top 50.  Sorry.

No, but it is generally considered Ben Jonson's best and most characteristic comedy; Samuel Taylor Coleridge considered it had one of the three most perfect plots in literature.