It depends a lot on where you live!
In the UK I'd say (from experience) that the best bet is Lamb/mutton. It is nearly always mosty grass fed, sheep don't thrive in "feedlots". Wild meat like Venison is a good bet too. Beef can vary hugely, if it's not grass fed on the label it's been fed grains.
I keep seeing references to "pastured Pork" which is a nonsense, Pigs are omnivores like us, they will nibble at grass but can't live on it! Most Pork is reared in factory farms and is kept indoors and fed concentrates. They are routinely dosed with antibiotics. Organic pork is not nessesarily outdoor pork though it is more likely. For pork my minimum standard would be outdoor reared.
Chicken, unless it's free range organic, has had a brief and miserable existance.
I am, I'm afraid, completely spoiled. We rear our own cattle, sheep, goats, pigs and hens. I have not bought meat in a shop for 6 years.
It sound as though you have worse food labelling issues in the USA than we have, and we thought ours was bad.
I think bulletproof exec has an excellent gradient that shows quality of meat on a scale.
In short, it's as follows:
100% Grass fed beef/100% pastured eggs > 100% Pastured pork > 100% pastured chicken > organic beef > factory-farmed eggs > lean beef/pork/chicken cuts that are not organic/pastured > other meat
I believe the healthiest meat is grass-fed ruminant (some kind of creature with 4 stomachs) and wild cold-water fish like salmon or mackerel. Don't forget to eat your liver.
Female, 5'3", 49, Starting weight: 163lbs. Current weight: 135 (more or less).
Starting squat: 45lbs. Current squat: 157.5 x 2
I agree that wild fish is an excellent protein source that is up there with the 100% grass fed cow. There is apparently less contamination in water than on land, so the food is a bit "cleaner." Depending on the fish, you won't have to worry too much about mercury because they also contain selenium to combat it.