When it comes to DPS, the Champion class is the best you can choose. But, when you are playing the role of a strictly DPS class in game, you'll find that you have to give up your skills of parry, block, or evade, which means that you'll take more hits. But, to counter this, you will gaim a higher power regeneration while you are in combat to help you stave off the attacks as much as possible. You'll also gain a better fervour regeneration than normal when you are forced to give up these attacks, as melee attacking is one of the main ways that you'll gain the fervour you need for special spells and abilities.
Since fervour is one of the main ingredients to making your Champion a great toon, you'll want to do whatever you can to up this so that you can use your DPS skills as much as possible. At level 15, Champions can use light shields, which will help you with taking damage and will also help with fervour regeneration due to the hits that you can now take. Then, at level 30, you'll complete a class quest that will allow you to gain your class trait that will allow you to use heavy shields and take on even more damage.