personally, I would pick allstar. I did both all four years of high school, and honestly looking back i wouldn't have even bothered with my high school cheer team. We were a small team and the coaches knew very little about the sport. We practiced in our cafeteria, and the majority of the things we did were illegal. I ended up fixing the competition routine at least 6 times because of preventable injuries, all because the coach thought you should do a full twist on the concrete floor, or do basket tosses with only 8 ft of ceiling space. It became dangerous to even stay on the team. We were a mess and I personally hated it. Now, I am in now way saying that high school cheer is like this as a whole. Many schools have great programs with staff who know what they are doing. But my school, along with pretty much all the other high schools around me, do not have this.
My allstar team taught me everything I know. I owe them for every skill that I have and all of the knowledge about cheer that I gained. I started off with nothing more than a janky forward roll, and am now working toward double fulls. I learned incredible stunting and tumbling technique that is both safe and strong. I felt very safe when attempting and learning any new skill, and always felt comfortable and assured that I would not get hurt, as opposed to my high school team. Now I cheer in college, and I can honestly say that I would have not made the collegiate level if I wasn't involved with all-star.
My entire state has generally rough-looking high school teams. I have seen some very scary tumbling passes and stunt sequences attempted. But, again, that may not be your situation. My question for you is what are you in this for? Allstar is not connected to the "traditional" aspects of cheer. Poms, megaphones, actual crowdleading, spirit, and cheering another team on are not incorporated. High school competition routines must incorp a cheer around 50 seconds or even longer, leaving you with only 100 seconds, or 1:40, of actual competition on the floor, as opposed to 150. (2:30) If you like the actual cheer part of cheer, if you like standing on the sidelines more than competitions, if you like cheering on other teams as the primary goal of the team, do highschool. If you prefer focuses on only competitions, no other teams connected, and a more fierce, competitive atmosphere, do allstar.