Here's the skinny on how each averages:
Calories Fat Saturated Fat Cholesterol
Chicken 160 6.5g 1.8g 78mg
Beef 160 6g 2.1g 69mg
Pork 154 5.8g 1.8g 66mg
Fish 107 2.9g 0.5g 63mg
Check out Pork and Health for a detailed chart.
Not only is pork among the healthiest meats, it is also a great source for Iron, Magnesium, Phosphorous, Potassium, Zinc, Thiamin, Riboflavin, Niacin, B-12, B-6, and of course Protein.