So they're both in the same class of medications.
Boniva has incredibly weak bone-building capabilities. Roche wanted to go to market with a once daily or once weekly dose but it didn't because it knew that it's head to head data versus Fosomax or Actonel would make them dead in the water.
So Boniva is marketed as once monthly - emphasizing dosing as opposed to true efficacy. That's the only way they can survive in the market.
So the true choices are Fosomax and Actonel.
Now before I talk about both, it's important to understand the difference between the quanity of bone built verus quality. You can build all the bone in the world, but if it's poor quality (think of a ladder made of foam versus made of steel) what's the point? The end result, for everybody, should be fracture reduction - because that's why osteoporosis is such an issue. Fractures and breaking bones can cause a great deal of other health issues.
Fosomax has what they call the F.A.C.T. study where they claim they build more bone than Actonel. And they do. But, it's not as good quality of bone. If you read the study more carefully, patients in the study who took Actonel had significantly less fractures than those who took Fosomax over the same period of time.
Side effects are also important - Actonel has significantly less GI side effects versus Fosomax.
The choice, in my opinion, is simple. Actonel's the only way to go.