2H Axe... the perks for the axe end up paying off much more than the other weapon types, plus the 2H sword and 2H axe actually swing the same speed, despite what the ingame loading tips say. We tested it in another thread, and had an exhaustive debate about weapon types, damage per second, etc. You can see for yourself, if you like:
http://www.gamesas.com/index.php?/topic/1313851-complete-character-design-freedom-damage-resist-caps-and-ridiculous-damage-thread-7/
A 2H hammer swings slowly, but does the most damage per hit. Don't bother getting specialization perks for the Warhammer, because very few enemies actually have/use armor, and none of them have much in the way of armor skills to make the perks worth investing in. For example, Dragons have zero armor. You can check this yourself by using the console if you have the PC version.
Also, with high smithing skills and appropriate perks, any self-improved weapon will do more damage than so-called fabled artifacts like Wuuthrad. That's in the thread, too.

-Loth