There's no official recommendation for which way direction your baby should face in a stroller. But you'll find that most strollers are designed so that if they're newborn-compatible, they are facing you directly in the stroller. Not only does this boost baby development, but it allows you to keep a watchful eye on your little one.
Once your child graduates from the newborn stage, forward-facing strollers, where they're exposed to the surrounding environment rather than you, are standard and most commonly used.