What is the best way to earn XP in multiplayer?

I've heard of people doing Pike's Basin in free roam, and I've also heard about doing quick runs of Twin Rocks. I want to know, which would give the most XP relative to a time period of, oh, I don't know, how about 1 hour? I ask this because I want to level up so I can get a better mount. ( My current mount is a Cleveland Bay )