Here is the best edition of « Kitâb At-Tawheed » by Imam Muhammad ibn Abdel Wahhab.
This edition was transcribed from two copies of his grandson, Shaykh Sulaiman ibn 'Abdillah, the author of « Tayseer Al-'Azeez Al-Hameed ». Moreover, the differences between these two copies and more than 30 other manuscripts of Shaykh Muhammad ibn Abdel Wahhab students are cited.
The matn is with all harakaat, the hadiths are referenced and authenticated, the book is prefaced by Shaykh Sâlih Al-Louhaydân and the author of the tahqeeq is Salafi. Saudi edition, also available in Egyptian edition in Egyptian edition and pocket edition.