My husband transferred to GSU from Carnegie Mellon back in the 90’s and crushed it at GSU, then got a teaching fellowship at U Miami (free graduate school and they paid him to go there). I also took classes at GSU (also transferring from CMU). It’s one of those schools where you get out of it what you put into it. There are some dummies, but there are some really brilliant, savvy people who are not your typical students.
Given that you have the three really good opportunities, I’d take the time to explore each school more in depth and talk to the professors in your major, and explore what it would be like to live on each of the three campuses. GSU and Tech are right next to each other, although the buildings and layout is a lot nicer at Tech (in my opinion). Athens is its own beast, and every bit as progressive (if not more so) than Atlanta.
You will work your butt off at tech. You will see some people you know at UGA, and there will be some people that shouldn’t be at college at GSU, and you may get robbed at gunpoint in downtown atlanta. There’s no perfect school, just the one that fits you the best, and only you can know which one it is by going and checking them out and talking to people. Boots on the ground…