The beauty of FFXIV is that you can be any and all classes one one character. I'd suggest just picking one you like the look of and giving it a go. As a beginner myself, it looks as if you ultimately end up leveling all classes anyway for the cross class abilities.

A dps will invariably have less responsibility than a tank or healer, it if you want to do one of those roles then you should. One thing to note (as a TOR player myself ) is that early tanking is much harder in this than TOR.