I don't think there is a correct answer to this question. The general advice would be don't go for something too young and green, but equally there are some very safe, sensible youngsters out there who would be much more suitable than some older horses. It very much depends on the individual horse.
Given your age and expereince - if your parents agree then I would suggest an older school master type. Its really up to them becuase they are going to end up with the bills but I would be looking at something 13 - 16+ Possibly older.
You might want to talk to admin and delete this profile because you have put your age on it. Things tend to feel safe becuase it is horses and we are all horse folk together - but you need to be safe online and this forum is not proof of that. Speak to your parents - but delete this user name and come back as something without your age on it. Always remember to stay safe online!
Make life as easy as possible for yourself, get an older horse who does (roughly) what he is asked, youngsters need varying amounts of time, effort and patience. As I have found out to my cost!
Sugar was 16 when I got her (first horse) and she's been great. Knows most things, still has plenty of enthusiasm for jumping and work, and she's pretty sensible.
Age breed and looks are a bit irrelevant when buying a first horse Temperament, health and kindness are far more important. You need a reliable safe sensible sort that hasn't learned to ditch its rider at every available opportunity