There are several ways to rate NFL players. Raw statistics are one option, while websites like Pro Football Focus use advanced metrics to determine player grades. The Madden video game franchise has its own ratings system—which has drawn a variety of reactions from players.
A wide range of information can be used to make a valid argument about the "best" players at each position.
When determining which players are the most dominant, however, things are more subjective. A player's ability to take over a game doesn't always show up on the stat sheet or in efficiency ratings.