Argentina is one of the safest countries for tourists, considering all the countries of South America. There are problems like theft and pickpocketing. So you need to use common sense when you travel and keep yourself safe. But these are minor risks that you can avoid with a little caution. But you also need to know that recently, crime has been increasing.
Bus terminals are often places where tourists may step aside from their luggage and may be in risk of theft. Families are traveling together, and one may think the other ones have a lookout for luggage. Even worse, they may be saying their goodbyes to other family members and may completely forget about their luggage. Be cautious all the time.