Not sure if you already made your decision or not, but I can offer some younger input. Born & raised in Garland, Firewheel area. My mom and some of my HS buddies still live in Garland after graduating from state universities. I went to Naaman Forest High School 2012-2015 and we had at least 6 of us I can remember that went on and graduated from A&M. Everyone will want to push to Sachse High School as it is nicer and better at sports, but you can get a quality education in GISD from most high schools if your head is on straight.
The GRCTC was a big project that I believe any GISD students can apply to and take career driven classes at. My HS friend teaches a class in there and the things the students are exposed to are pretty neat.
https://www.garlandisdschools.net/grctcEvery school will have a diverse mix of kids as Garland was once the 6th or 7th most diverse city in America at the neighborhood level (circa sometime 2010's). We had choice of school if you can provide your own transportation, otherwise the buses would route you to the nearest school.
Firewheel neighborhoods around the golf course have an aging population with houses going on the market more frequently and new young families moving in. As others have said, there are some rougher parts of town but I would have no issue raising my family in Garland if the opportunity arose. Its close enough to go to downtown Dallas at a moments notice, but far enough away to to avoid big city messes.
Lavon, Sachse, Wylie, Rowlett, and Murphy would be good options to look into as well