Bison Versus Grass Fed Beef- Which is Better?

Both!

The more variety, the better; this goes for proteins as well as produce.

The most important things are:

• To make sure either meat is 100% grass fed.  It needs to state that, otherwise, without the 100%, it can be legally called grass  fed, even though it may be grain finished.  Argh.  Another blog topic!
• Also, make sure that the animals were raised humanely and treated as living beings, not as mere commodities, treated with cruelty as we’d see in mass market meats courtesy of Monsanto and the like

Grass fed bison tends to have a higher protein content, ounce for ounce, than grass fed beef, and a higher CLA and Omega 3 content.  It also has more iron.

Any downside?

Not at all; except that you may need to be slightly more diligent to cooking time as, due to it’s natural lean constitution, it’s easier to overcook.  Overcooking meat is just..wrong.

So then should one always opt for bison over beef?

Not at all.  Just as I’d never suggest only eating wild salmon and never eating black cod,  I’d also not suggest limiting the types of protein you include in your versatile, Paleo diet.