An Elo rating is a points-based system for rating competitors. The Elo rating system uses actual performance data (wins and losses). If a team wins more games than expected, it’s rating will go up. If they lose to teams that they should beat, the rating goes down. 

I like the Elo rating system because it is dynamic and reacts to actual results. This means that, theoretically, the model gets more accurate over time as more data/results are inputted into the system.