You are actually already playing the class that best fits the ''all-out damage'' you mention. If you like huge damage numbers on single targets and awesome AoE spells, then stick with it. Plus having infinite MP is always fun.

Otherwise, if you prefer melee damage, then both Dragoon and Monk are good choices. Monk is more position dependent but can inflict a bit more damage than Dragoon in optimal situations (i.e. fights where the boss stands still).

You can always try out more than one class once you've played the main story to level 10 and get the ability to change classes.