Norse Berzerkers? That's the funniest ever name I've ever heard a Space Wolf been called.
Mine's Roboute Guilliman. What can I say? I collect Ultramarines.
I like Guilliman because he's a master strategist, with one glance across a field of battle, he could see where the enemy had gone wrong, and would make immediate action for his forces strike where they would cause the most damage.
Also, because of the fact that he wrote the mighty tome, the book whose holiness is second only to the Warhammer 40,000 Rulebook, the Codex Astartes itself. This book details all things military about the Imperium and includes how their hierarchy should function, the best tactics for them to use in almost every situation plausable. It even gives tactics for individual units. This book has been used by the Imperium for over 10,000 years, and is still in use, guiding the Imperium's soldiers against the terrors of the Void and the Warp and the mind. In fact, the only things it doesn't mention are the Inquisition's Holy Ordos and their allies i.e. Grey Knights, the Ecclesiarchy and their Sister's of Battle, the Exorcists Chapter (who are different to a normal Chapter because they are also joined permanently to the Ordo Malleus so that they can help the with the Grey Knights' relatively low amount of troops).
Not only that, but below the mighty Fortress of Hera, in a large vault, Guilliman has over 30 tomes, surpassing by far Marneus Calgar's mere 28, and all describing, in detail, each of his many conquests (and each tome contains more than one battle story).
Best of all, Guilliman is the most likely one to come back. Although at the moment kept in stasis, some say, that by either some freak natural occurence, or by the will of the Immortal Emperor, that his wounds are healing, and that he will some day rise from his throne in the Fortress of Hera and once again purge the xenos.