I wrote an addon that looks at my situation (usually a daily) and writes a macro under my backslash keybinding to fit, e.g. if the addon notices I've flown into Jotunheim and I still haven't completed the quest, the addon will write me a macro /use Ebon Blade Banner. If the addon sees that I've pulled up to a harpoon, the macro becomes /cast Rapid-Fire Harpoon. It's wonderfully mindless but not very flexible -- if I haven't done it before, it's probably not going to be supported yet. In that rare event that I want to equip or use an item that isn't already covered, I write a macro under my alt-backslash keybinding, then invoke another addon that copies that macro to each alt. It's only slightly cumbersome but works really well.