I don't see any great thing about being 25 again, save the chance to plan for my 30s a lot better.
25 was really just a turning point in my life. I am pretty sure on my 25th birthday my body literally started to feel
If a magic genie gave me the chance to go back to being 25 I would. But if they have me the chance to go back to 27 I would do that to. But if they asked me "how far would you like to go back." I would say somewhere between 12-23.
Those where not only years that I could have used to shape my current life a lot better but they were also years when I had more options to being social. I mean being social was hard for me then, but I had "friends" and I know I could have had more. I was even invited to parties and there were even girls who now I realized actually liked me, but I was too scared to act, and I always thought there would be time... there wasn't.
I find it odd that you say a lot of people say they would go back to 25, because to me 25 is when living with SA becomes especially hard. Your peers really start establishing themselves at 25, everyone around you starts getting careers and married and having kids. If you are stuck in the same place people really start to notice at 25.
I would redo 25 if I could, but I can think of better years to redo.