Sherlock Holmes books. Which is the best?

I watched Sherlock on Netflix and now I wanted to read these books too.

I googled a bit and I found a lot of different books. Most of them looked strange or were very old.

Which is the best Sherlock Holmes book? Are there also good book series?

Please share your opinions with me.

If it's just about reading: the original works of Arthur Conan Doyle are in the public domain, so they can be downloaded anywhere for free.

Otherwise: The Original Illustrated Strand Sherlock Holmes: The Complete Facsimile Edition (Wordsworth).

You can forget about translations and are superfluous because of Doyle's children's English.