Which rogue character should i use in Dragon Age 2?

Both are powerful, but Varric has the edge. His abilities are just slightly more useful than Sebastian. Varric also has more to add to the story. But, you can give Sebastian any bow in the game. If you are the kind of player who pays attention to enemies weaknesses Sebastian may be a better choice. you can swap out his weapon as needed unlike Varric who only uses Bianca.