It's important to leave room for both qualitative and quantitative analysis. While it's good to know that Team A has 85% in scoring, it's also good to know that you can demolish them by bumping them in the rear right corner. I'm going to link you to
what one coach likes to see from her scouters, though I'm sure there are many other possibilities that are equally as good if not better. Hopefully you'll at least get some ideas from that. (Sorry for the outside link, but it was a lot to paste in.)
Edit: Also, I'm not sure if this is something you can specifically scout for from the stands, but by interacting with teams through pit scouting, and talking to your coach who has worked with teams on the field, please check up on
teamwork. If a team has a great robot, but is unable or unwilling to work with other teams, achieving success with them will be very difficult. Look carefully at how they interact with others, and if they are willing to compromise to bring success to the entire alliance.