That is such an inappropriate question to ask of anyone.  Boy some need lessons in tact and social graces.  And you just joined to ask such a tacky question?  WTF?  
I guess you gotta try them all before coming to a scientific conclusion  

  So stop asking and get busy because you have your work cut out for you!  
Where I used to work, someone WHO CAME TO DROP OFF THEIR KID asked me that (like I would know the answer).  My reply to him:
"dunno, why don't you ask your wife!"