to be honest, when you say a small school, I think if the village schools round here where there are 30-50 kids in the whole school. That is a small school and for many reasons I would sadly say avoid at all costs.
But 1 form entry isn't really small. It is plenty big enough for variety and for lots to be going on. Big enough for there to be a football team and small enough that you might actually get a chance to play.
I think that 2 form entries can be just as family feeling and have a good atmosphere, but it takes more work. A good head will make all the children feel that they belong and take pride in their school, and no reason why the head shouldn't know everyone. It isn't that hard.
One big advantage of 2 form is if the class dynamics don't work, they can remix the classes between years. This can be really helpful, and a 1 form can get a bit intense if there is an issue with someone in the class.
But on the other hand, my dds school (1 form) felt they needed to remix a class, so they created a 2 classes with year 5/6 mix, which actually worked really well.
Once you get larger than 2 form it gets harder to get that family feel.
in the end, I think the caring etc is really down the the staff, and it can change year on year. Good head, enthusiastic staff, school that attracts teacher applicants, well motivated = great school.
If for some reason some of the above are missing then it gets harder to get that lovely feel, and to get the good joined up care.