If you have a very active child, space to run around in. The best thing about my DCs school is the massive field used for a lot of the year and the large playgrounds. Without the chance to blow off steam my DS would have found school a lot more difficult than he did., and he did find having to be still and quiet in a classroom very difficult.
I'm not that interested in high academic achievement at primary, and especially not in eyfs and Ks1. Lots of play, being outside a lot, nurturing staff, preferably low staff turn over., all these things are important.
Availability of after school club, that again gets kids outside and playing and also availability of childminders that pick up and drop off at the school. There is a lovely small village school near us, no point in even looking round, there is no after school club and not a single childminder drops off there.
Not so sure that organised tours or even questioning the head are much use. Any opportunity to see the school working normally, and the head interacting with the kids, these are useful. Go to the Christmas fair and check out how the head interacts with staff and pupils.
And while Ofsted reports are not the be all and end all, having had kids in a primary that requires improvement, it caused 3 years of upheaval , rapid staff turnover, very few clubs being run and though now much better, is not yet back to the happy relatively relaxed place it was when the kids joined. Only 1 teacher from the old regime remains. So I'd say, stick to the good and outstanding ones if possible as all that upheaval has definitely had a negative impact on my DD's education, it was very disjointed for 2 years , she had many different teachers, and the way the school taught things altered several times, which was confusing.