According to an evaluation of early childhood education services performed by San Francisco State University, two important traits of an ECE program are having instructors who understand the many different emotional and behavioral issues of children and having access to early childhood support networks available nationally.
An excellent resource to find the best early childhood program is the National Association for the Education of Young Children, whose website is NAEYC.org.
The best tool to use when deciding on a provider is your own parental instincts. If you end up with an unmistakable negative "vibe" when you visit a particular program, chances are your child will be much better off elsewhere.
Quality programs are not always staffed with veteran teachers. Occasionally, a program staffed with newly minted graduates is just as good as a program with veteran instructors on its staff.
While the Montessori program is quite prevalent and preferred in many Early Childhood programs throughout the world, the Waldorf approach, which focuses on a mostly cognitive learning environment, is embraced widely as well.