The giant anteater gets its food by looking for an ant hill, then it sticks it's tongue in the hole where the ants get in. The anteater will wait a few seconds for the ant to get on the tongue. The anteater will put its tongue in the mouth and swallow.
Definitely the giant anteater would be much more dangerous. A platypus would only pose a danger if it is improperly handled. However, an angry or threatened giant anteater is capable of disemboweling a human with one swipe of its front claws.
There are many species of anteater, and each one has its own conservation status. The giant anteater is considered Near Threatened, but not quite Vulnerable. Other anteater species are considered Least Concern.