I don't understand your question; are you wondering whether you should give through the donation-matching pledge or about whether you should give to AMF or SCI at all?
No, I'm wondering exactly how much more valuable the donation-matching pledge is than giving directly. If you'd rather do something else with the money than donate it directly (such as hold on to it to see if you can find something better), but you don't think that would be twice as good as giving directly, it would be important to know exactly how useful the donation match is.
As of today, GiveWell has two new top charities:
1. Against Malaria Foundation
2. Schistosomiastis Control Initiative
Their previous top charity, Village Reach, no longer has much room for more funding. Which is a good thing: partly through givewell's influence they now have as much money as they can put to good use.