Both a Taco and a Grilled Cheese Sandwich are inanimate objects. Therefore if they were put in a ring together they would just sit there and go mouldy.
However, if the competition involved Tacos and Grilled Cheese Sandwiches that had been magically turned alive then I would say a Taco would win....I don't know why though....maybe because Tacos are AWESOME! Oh and BTW - Try not to turn this topic into spam, please write why whichever thing would win....Don't just write Tacossssss (*cough* RaiderDawg *cough*)
tacos would charge toungun by circulating savor flavor energy throughout the taste buds charging the toungun when it was eaten burning the grilled cheese and win
A taco because most tacos are hard shelled and it could attack the sandwich with it's outer coating but then some fan might eat the taco. Or a fan who just happens to be a cheese lover smells cheese and goes to the sandwich then eats it then tacos win!