They're quite different types of players. Falcao is the main striker with amazing finishing abilities both with feet and head, while van Persie is better as a second striker. While van Persie also can play as a lone striker, he can perform the best as a traquiresta with a striker partner or inside forwards from wings.
So if you'll use more supporting wingers with good crossing abilities, then Falcao will be a better choice as an advanced forward or target man. But if you want your wingers to have more attacking roles, then use van Persie as a traquiresta.
My choice is to use them both as van Persie's great passing and crossing abilities can feed Falcao greatly.