Basically any melee build that is focused on doing physical damage, and also the ones that aren't. The 2 builds you mention are prime candidates for such an awesome weapon, but really any melee build would benefit from such a behemoth weapon. I'd stick with a Zeal paladin, with Fanatiscism, for fast attack speed and insane damage.
I have done both zeal pala and ww barb when using botd ba. And both chars are awsome. But i think ww barb is better. Put 1 point berserk and you can kill physical immunes and all other monsters using ww. With zealer its hard part because you do only physical dmg. Unless you do frost zealer. And then you get other problems.
The answer to physical immunes for Pally is Vengence, which deals added elemental damage. With a high damage weapon like Botd, even a single point in vengence is enough. I use F1 for Zeal, F2 for Vengence.