Look for spark accrediation...
SPARKS simply means the centre has all the necessary paperwork done but doesn't necessarily mean it is of high quality.
To fulfil SPARKS, the centre has to spend a huge amount of time getting all the documentation ready, often at the expense of interaction time between staff and children.
Example, teachers may get children to "pose" for motor skill assessment in the child's portfolio even though the child may not have reached the stage.
Another example : A centre has to pass all their teaching materials to help another centre of the same company to attain SPARKs because the latter has failed repeatedly to get the accreditation. So the cluster principal asked the centre with the SPARKS cert to "share" their teaching materials.
How do I know? I have been in this industry for 30 plus years and have held various roles. I also have friends and ex colleagues who are still in the field and we exchange stories often.
The best is to go down to the centre and observe how the staff interact with the children. Visit is best unannounced as the centre cannot prepare before hand.
Teachers should treat everyone, including children, with warmth and respect. They should use positive discipline rather than threats. Children should be engaged in activities that stimulate them and encourage social skills. The principal should spend more time mentoring the teachers rather than doing admin work. He or she should know each child in her centre, as far as possible, and welcome any constructive feedback from staff and parents. Staff turnover is also a good indication of management style.
I would avoid big chain private operators in general as most are in this business for the money only,especially those that use fanciful educational terms to sell their services eg they follow the latest brain research etc. These are just fancy titles to charge higher fees. Ultimately, whatever research is of little use if you treat your staff like money making tools and staff are unhappy and unable to translate the research into their daily practice.