Jonathan Stroud is a genius,
The Barthimeus Trilology was the first books I read in french, and after Raymond Feist, he is the second Fantasy author I have picked.
With Barthimeus or With LockWood & Co, we have 2 very different world, but both very close to our own a from a few decades ago. The fusion of the Fictional world with the 'real' world is very well done. What makes this books really good to read is the story but also the humour.
If you haven't read a book of Jonathan Stroud yet, you are missing something in my opinion.