Absolutely most important is a developing a love of learning. The early years, up to seven, should focus primarily on this. My son (aged 5) has moved from a later school start country to an incredibly early start country (legally five but in reality 3 or 4 at the latest). He has gone from being a child who loved learning and believed (rightly) that he was good at it, to a child who resists learning as he believes he is no good at it. Surely that is the opposite of what education should achieve. I volunteer at a school nursery and I see how this incredible early formal learning crushes the natural and deep learning of children through play, to make them sit, wriggling and protesting, to do unnecessary formal learning. For example, one three year old was forced to dismantle a construction he had spent a long time working on, including making mistakes, reflecting on them, correcting them. He was learning maths, physics, construction, science all through practical application, as well as persistence and experimentation and planning. He was forced to abandon all this (teaching him that his efforts are unimportant and unacknowledged) to sit on a mat and partake in a days of the week song, which he had no interest in. That is a poor educational approach.
Overall, including in the later years, I want my children to learn to love learning, to learn their voices and contributions are important, to learn that not succeeding at first is part of learning. I want schools to recognise that rich free play, especially in the primary years, is an important part of a child's learning. That is where they experiment and explore on their own terms, where they learn to socialise and collaborate on their own terms. When I see schools with barren play grounds I know they don't have a deep understanding of children or children's learning. They see the curriculum before the child.
I think facts and knowledge are important too. How to think is crucially important, good people skills, confidence and a have a go attitude. Believing that 'you' matter and owning your right to speak and communicate. Ability to work with others. Good empathy skills. All of these are built through free play as well as formal education.
I think what I am essentially saying is that I want a school with a clear conceptual, theoretical and philosophical underpinning which is rooted in a clear understanding of children and childhood.