The best meat you can find is grass-fed AND grass-finished. Meat that is grass-fed and finished is much more nutrient dense compared to grain-fed meat.
The reason why it is important to also have the meat be grass-finished is because most cows are fed grass at the beginning of their lives, but then they are often transitioned to a grain based diet to increase their size. Many companies will still label this meat as grass-fed because technically these cows were fed grass for some portion of their lives. However, this grain-finished meat will lose a lot of the benefits that come along with grass-fed meat.