Ah, you speak of specific warriors, now?
I'd have to say the Warden, then. The PC Warden can potentially take an improved Joining potion that enhances the Taint within them. This gives them an edge in combat. Warriors can become Spirit Warriors/Reavers/Templars, and Mages can be Arcane Warriors/Blood Mages.
The PC Warden also has a very impressive history:
Has slaughtered abominations, darkspawn, demons, soldiers, lesser dragons, werewolves, golems, and reavers
Defeated several, powerful creatures. The High Dragon, Gaxkang, Flemeth, Shad Wyrd, The Archdemon, The Architect, and the Mother. I've probably missed a few.
Has defeated probably the best general Thedas has seen in decades, perhaps centuries, in single combat: Loghain.
Also has access to the Sacred Ashes, which gives the PC a free heal from anything!