WW uses DW unless the 2H is a lot higher iLevel. BrM use highest iLevel or DW if given the choice.
Let me clarify so misinformation isn't being passed around... When gearing, BrM and WW use the best weapon, or best weapon combo they have. Dual-Wield is preferred for WW if weapons are equal iLevel.BrM is entirely preference. Many have found that dual-wield has slightly less elusive brew generation, BUT more consistent than two-hand. I personally prefer a two-hander because of the haste bonus it provides. I find the "rotation" more smooth with a two-hander. Note: A lot of BrM monks including EJ, Blood Legion's MT (Riggimonk), and Method's MT also prefer two-hand. This doesn't mean you need to use a two-hander. If equal quality, try both and find what you prefer.