It's been mentioned already, but I'll reiterate that you should play several different classes to ge a feel for what you like. Try a Monk, Rogue, Barbarian, or Warrior to get a feel for strictly melee classes, a Paladin, Shadowknight, or Ranger for hybrid classes (melee + casting), and a Magician, Cleric, Wizard, Necromancer, Druid, or Shaman for casting classes. Or any combination of the above.
What hasn't been mentioned is that you shouldn't get too attached to your first puppet since you'll likely end up playing something completely different than what you eventually decide will be your "main" puppet. It may seem like slow-going at first, but remember that you'll have many weeks of playing that should be thought of as a learning experience. In the overall scheme of things, the first month or two of gameplay is just training to see what sort of class you like best. There's plenty of time to develop what you decide is the best fit for you, so don't feel like you have to immediately decide on something and maniacally work towards getting that puppet to 75. There's an unbelievable amount of content available to all levels and classes, and you should take the time to enjoy the journey :)