if you have to have one, which i do not think you do, most or least points in the graveyard. whichever you choose can have solid argument against it. most points means i have either been very active, or have had a lot of stuff killed. least points, perhaps i have been super efficient, or turtling and hoarding mana for very large things. either way does not give a good indication of who is winning. looking at the board state, cards left in the book is the best way to forecast an eventual winner. but that is not possible. hence ties should be just that. ties.