Multibox assistant: multitool (does a lot less than jamba, in a good way, if that's possible)

Bar replacement: Dominoes - simple and easy mostly to see cooldowns and have something set for solo play, autobar - for food/drink/mount/quest use items, ISboxer for extended macros on raw keybindings (takes no bar spaces)

Map replacement: carbonite, gathermate, gethermatehud (on herbers and miners)

Bag replacement: arkinventory - does bank and bags

Quest assistance: carbonite (on all for sharing data), and tourguide on main only (and disabled most of the time on 80s)

Party/raid frames: ag_UF - small and simple, shows casting bars and predictive healing. Open RDX, big and complicated for click casting of heals and cures

other addons on all: advanced trade skill, postal, tekKompare, Titan, WIM, ZOMGBuffs

other addons on just main: DBM, Elk buffbars, quartz, auctioneer, omen, recount, msbt, chatter, atlas