3 I see as viable for pretty much anything, including multiboxing is FuBar, ag_unitframes and Bartender3

Not only are they in my opinion awesome addons, they are also ace addons, so very easy to keep updated at all times

This comes from a guy who has several compilations lying around, and a min use of 140 addons. For one character of course, I haven't started anything serious regarding multiboxing (yet!!).

I have been through most of the addons, I believe