Arabic is a root-based language. The best PDFs show the 3 or 4 root letters next to the word. For example, seeing that "كتاب" (book), "مكتبة" (library), and "كاتب" (writer) share the root K-T-B helps you learn 5 words for the price of 1.
The gold standard is the book "A Frequency Dictionary of Arabic" by Tim Buckwalter and Dilworth Parkinson (Routledge). This is the source file for nearly every "free PDF" online. 5000 most common arabic words pdf best
While having the list is great, the method of learning via a static PDF has significant drawbacks, particularly with Arabic. Arabic is a root-based language