Your initial feeling will be the main reason for selecting a school.
How did you feel when you walked round the school?
Ask to observe a class teaching maths or literacy, and ask to see older classes as well as reception.
Where the children happy, engaged? What did you think of the teaching style, what was on the walls?
Do they focus on academics or arts (all schools have same targets but have individual priorities)
What do they offer for the children - sports, clubs, after care etc
Playground facilities - are they allowed to play out when it is raining. Can they get dirty? Are the kids smart clean and tidy, or grubby and happy?
What is the teaching style, is it formal, or very much learn through play, or somewhere in the middle. (schools are different).
If you are interested in academics, results, etc., ask questions and see what responses you get. SOme schools cant be bothered telling you, others will be very informative.
What do the schools do to develop the whole child needs, social, interaction, etc in addition to academics.
Ask locals for feedback, shopkeepers, neighbours etc., for reputation, views, comments.
My choice of school was changed at the last minute when I went to visit a school that I had always written off, because of the area it was in, and it was fantastic.
You and your friends will have different ideas of what is a good school, but you need to find one that YOU like and feel comfortable with.
If you still cant decide, look long term and the feeder system into the high school.