I remember after the first few years of A-Rod's career saying that if this guy keeps this up, and as young as he is, he will be by far the most dominant hitter ever to play the game. So far so good, and congrats to him.
On a side note though, as far as pure power, I believe Mark McGwire is the best hitter to play the game. Doesn't he have the highest home run to at-bat ratio? Perfect example of why I say if A-Rod stays healthy.