What discipline are you? In lower level eventing you can have the mane however you want; however, most people pull it to keep it short and thin and out of the way. Hunter jumper is different though. I don't know a whole lot about their world but I do know that they are pretty picky about looks so you would probably have to braid it (and that usually means pulling it, as it is really hard to make a long, thick mane look good in hunter braids). Do you know how to pull a mane?
He knows when you're happy; He knows when you're comfortable; He knows when you're confident; And he always knows when you have carrots.