Youth Restoration? It'd be horrible, going from a strong, independent, miserable, thirty-seven year old man, to a weak, five year old child, being dictated to by everyone and bullied by my older brother. No freedom or respect at all. I'd love a second chance at school, but I'd just knuckle down, do the best I can at my grades, try to be as athletic as I can and try to avoid trouble. It'd be a real exercise in patience and focus, with a potentially big payoff as a young adult. I have a lot of regrets, but I'd have to suffer to rectify it. Also, I've really started to age over the last couple of years and my blood clot really had me worried, so extending my life sounds great. I'd also try to help my missus. She's a few years older than I and although she was successful at my age, her divorce caused her to go off the rails and make mistakes that cost her her home and put her in a poor paying job well beneath her. I'd like to track her down, but I'd only be friends with her and try to help her. Problem is that by the sounds of it, I don't think she'd give me the time of day.
Invisibility? Sounds exciting and a bit naughty, just to see how other people live. I don't think I'd commit crimes though, or even steal from people.
Teleportation just sounds fantastic. I'd teleport all over the world. However, if I have $1,000,000 waiting for me at twenty-one if my youth was restored (I think it would be 2007 at 21?), I could get my own home, mortgage free, and spend more of my youth travelling anyway. I could also manipulate certain stock or get lottery numbers if I had prep time, making myself richer.
Yeah, I'd pick Youth Restored.