[Philip W.]

I would have to say that the CENTER based system is best. The system is very general and simple, and uses really basic instinctive visual descriptions/interpretations. It will definitely depend on one's use of descriptive language though.

The problem with the number system is the preparation of the mind. People will have to begin memorizing the numbers each goal is represented by. When someone is going to refer to the far right goal, they'll have to recall the number that represents it, which may take a while longer for some people. On the other hand, over time and practise, the referencing will become easier from experience, but not everyone can do it.

Flash cards, as nice as they sound, are too much to handle, literally. Having a ton of flash cards in your hand, selecting the right one, and showing both teams of your alliance the card where they have to take their eyes off the field will end up having them all fall on the floor.