Abul Kalam Azad
Maulana Abul Kalam Azad wrote in the Zamindar (16 June, 1936):
"You enquire which one of the two Ahmadi groups follows the true path, the Qadian group or the Lahore one. In my opinion neither is on the true and right path, but the Qadian section has gone too far in its ghuluww, so far that the very fundamentals of Islam have been shaken; for instance, its belief that for faith and salvation the known and admitted doctrines of Islam are not now sufficient and that it is essential to believe in the Mirza Sahib of Qadian. But the Lahore group denies this ghuluww; it neither confesses a faith in the prophethood of the Mirza Sahib nor does it add any new condition to the conditions of faith; where it has stumbled is in the misplaced belief which it has created for the Mirza Sahib."
Writing about Sayyid Muhammad of Jaunpur who claimed to be the Mahdi, the Maulana says:
"The affair of the Sayyid of whom we are speaking is full of wonder, and various sorts of claims and absurd sayings have been attributed to him. What the followers of a person say need not be paid attention to, for whomever a people take for their religious leader they would raise him to no less a dignity than that of God-head, and if they are very careful they would not keep him below the position of a prophet. But some recent writers have written things which at first sight cause perturbance. Shah Abdul Haq, the Muhaddath of Delhi, writes: 'According to Sayyid Muhammad of Jaunpur, every perfection possessed by the Holy Prophet Muhammad was also possessed by Sayyid Muhammad, the only difference being that there it was in asalat (possessed originally) and here it was by tab'iyyat (attained by following), and by following the Holy Prophet he attained to such a place that he became like a prophet.' Reading these words of Shah Sahib, it occurred to me that in our own days a big section of the followers of the Mirza Sahib of Qadian entertain an exactly similar belief about the Mirza Sahib and lays the foundation of all its ghuluww (exceeding the bounds) and ighraq (exaggeration) on this difference of asalat (possessing originally) and tabe'ijyat (attaining by following)" (Tadhkirah by Maulana Azad, 1919, pp. 30, 31).
Again, regarding Mirza Ghulam Ahmad Qadiani:
"He is a mu'awwil (one who explains a word as conveying a significance quite different from its ordinary significance) and a mu'awwil is not necessarily a kafir."
(direct quotes extracted from http://www.musalmantimes.com/?p=1197, originally written by Maulana Muhammad Ali and available on aaiil.org)