I have read both Mazhar ul Haq and Sohail bhatti's versions. Both are very bulky and lack appropriate study on Spain. Yet, Sohail Bhatti's book is better due to its headings and proper placement of information which makes it easy to go through the heading in final revision.
But, you will have to study K. Ali's book too in combination with it, K.Ali's book is very small and brief and can serve the purpose alone but for good score, you may need both Sohail Bhatti and K Ali.