Sippy cup or cup with built in straw are the best options. A baby could find a real straw to be a choking hazard. BTW, Syag, you probably have very advanced babies, bli ayin hara, but every baby I have ever seen takes the cup and turns it upside down at the age at which you think they should be drinking from a cup. Perhaps with someone HOLDING the cup for them, they can be slowly taught, but on their own, most will toss the cup around. That’s why I never gave anything BUT water in a regular cup. Sippy cups are a good transition from the bottle, if the baby is bottle fed, and the cup with the built in straw works well, too.
DON’T give a baby a juice box with that tiny straw.