Two potentially big prizes are still several years away -- boceprevir for hepatitis C and the anticoagulant SCH530348. [Actually, SCH530348, also called TRA, is an antiplatelet drug rather than an anticoagulant (#msg-23899164).]
I believe that anticoagulants is the superclass for antiplatelets. (Also included in anticoagulants are antithrombins and ...)
I have not yet figured out whether we really know whether one of these subclasses is better than others for different indications. E.g. Evidence is mixed whether aspirin works to prevent DVT but it does work for prevention of MI.