JUST A MINUTE, wait... think a little  with cool mind. I don't think this voting is required at all for the Prophet Muhammad sallallahu alayhi wasallam to be the man of history or the man of the century.
Why??
Because:-

1. Prophets are selected by Almighty Allah .
2. How  can the created (mankind)  be competent to pass judgement on the selection of  The Creator .
3. The  authority for judgement of gradations among Prophets can only be The Creator Allah  and presently the message of Allah   which exists in true,  UNALTERED form in the Holy Qur'aan, in which Allah  forbids human beings  to discuss or comment on gradations of Prophets.
4. We  muslims  don't cast  votes  for  or  against  between two Prophets!! for we do believe in JESUS CHRIST's gradations as much as we believe in Prophet Muhammad sallallahu alayhi wasallam. Whereas  by casting votes we favour  one personality  and NEGATE the other.
5. Is Quality really  determined  by MAJORITY ???  OR is it in MINORITY?? Look around you for the answer, and it is quite clear. If Quality was really in abundance (MAJORITY) then this world would have been a paradise with majority of its population as No.1.

Does voting really makes someone  as No.1 ??.....Then look at some of the popularly elected Heads of States. ...What all they  do ... as No.1,  are the DEEDS No.1 ??  well not necessarily...
6. While voting for personalities we require ample knowledge of their qualities!  Is it really possible in case of Prophets ?  Well think for yourself dispassionately, Is VOTING  really the criteria for gagging Prophet Muhammad sallallahu alayhi wasallam as No.1 man in the history of mankind
7. Islaam has altogether a different concept in voting. It does not encourage open voting for a specialized subject, but allows a selected few to participate.  Voting generally, holds good only for our day to day life in the management of our affairs with each other.
8. So relax, no sweat for all the Muslims in particular and  mankind in general. Prophet Muhammad sallallahu alayhi wasallam  was, .......is ...... and will always remain as the  selected No.1 MAN IN THE HISTORY OF MANKIND