First of all India was NOT under Muslim rule for 1000 years..I guess you are not including South-India,Marathas,Sikhs and Rajputs in your INDIA..
Regarding Muhammad Bin Qasim,Mahmood Ghaznavi and Muhammad Ghouri..
They were looters who had a great fighting force at their disposal who plundered the Hindukush region and this was a normal thing those days..
If i have to choose the most powerful King in the Indian subcontinent , I would choose Chandragupta Mourya , Ashok , Porus (i know many people here believe that Alexandar defeated Porus but what i have come to know after extensive research ,thats not the truth.) , Shershah Suri , Hyder Ali,Tipu Sultan and Maharaja Ranjeet singh..