You could try something like this:
; Script: highest_score.sqs
; Find the player with the highest score and display this.
; If two players have the highest score, the first that
; is found is announced as the winner.
; Create an array that contains all the players. Yes, you will have to change this.
_players = [Player2, Player3, ... , PlayerN]
_highest = Player1
_counter = count _players
#loop
; Decrement the counter.
_counter = _counter - 1
; Exit the loop if the array has been traversed.
?(_counter < 0) : goto "done"
; If the player at the current array index has a higher
; score than the previously highest player, set him as
; the highest.
?(score _highest < score _players select _counter) : _highest = _players select _counter
goto "loop"
#done
; When you get here, the variable _highest will be the
; player with the highest score. Zoom in on him, elevate
; him to a godly state, blow him up, your choice really...
titleText[format["%1 is the winner!", name _highest], "PLAIN"]
exit
Run it when the mission is over.
Pope Zog