My Word can beat up your Word
J, 100

z=:"."0@":@(+/)^:9@(64-~a.i.])@(#~' '&amp;i.)"1
f=:*@-/"2@(z@((]#~]i.~{.@\:~)"1^:([:=/z))){'STALEMATE'&amp;,


runs like this:

f 'NO',:'ZOO'
NO       
f 'CAN',:'BAT'
CAN      
f 'FAT',:'BANANA'
FAT      
f 'ONE',:'ONE'
STALEMATE


it doesn't yet accept input exactly as asked.