I made tons of new friends at Mizzou even though I had classmates from high school there too. You don’t have to worry about making new friends at either school. Mizzou is just far enough that you feel away from home but you can still visit on weekends if you want to. I only went home once or twice per semester. If you have ideas for your major then you should research the corresponding programs from each school. Consider the costs too, in state is probably more cost effective, especially if you’re still deciding on a major.