these addons are based based on the assumption you are using default or elvui

on curseforge, make sure you are downloading the wow classic version of the addon (bottom right under recent files)

https://www.curseforge.com/wow/addons/acp
manage addons ingame (enable/disable, you need to restart game if you're installing new addons)

-Quality of Life -

https://www.wowinterface.com/downloads/info24947-AdvancedInterfaceOptionsClassic.html
restores removed interface options

https://www.wowinterface.com/downloads/info24989-OmniCCClassic.html
adds text timers to cooldowns, items and buffs

https://www.wowinterface.com/downloads/info25006-ClassicAuraDurations.html
adds little non-text timers on target (good with omni-cc)

https://www.wowinterface.com/downloads/info25004-WeaponSwingTimer.html
tracks swing timers for yourself/target (includes hunter auto-shot and wands)

https://www.wowinterface.com/downloads/info24925-ClassicCastbars.html
adds castbars to target frame // timer may not be accurate due to API limitations

https://www.wowinterface.com/downloads/info25000-ClassicSpellActivations.html
lights up ability on hotbar when it procs

https://www.curseforge.com/wow/addons/speedyautoloot
loot faster

https://www.wowinterface.com/downloads/info25150-BagFreeSpaceCounter.html
little free space text on your bagbar

https://www.wowinterface.com/downloads/info25015-EZJunk.html
auto sell junk

https://www.wowinterface.com/downloads/info24922-VendorPrice.html
vendor price

https://www.wowinterface.com/downloads/info25078-BetterVendorPrice.html
vendor price on crack

https://www.curseforge.com/wow/addons/clicklinks
clickable links in chat

https://www.wowinterface.com/downloads/info15636-tullaRange.html
spells are red if out of range

https://www.wowinterface.com/downloads/info25010-ClassicAutoDismount.html

- UI -

https://www.curseforge.com/wow/addons/inventorian
bag addon

https://www.curseforge.com/wow/addons/mapster
map with coords and unfogged zones

https://www.curseforge.com/wow/addons/tomtom
map waypoints

https://www.wowinterface.com/downloads/info24980-QuestLogEx.html
larger quest log

https://www.wowinterface.com/downloads/info25118-DejaClassicStats.html
more character stats (move speed, repair cost, hit rating, resist, etc)

https://www.curseforge.com/wow/addons/xptracker
https://www.curseforge.com/wow/addons/xtolevel_classic

-da big boiz-

https://www.wowinterface.com/downloads/info24994-Questie.html
quest addon

https://www.curseforge.com/wow/addons/ezquest
quest auto-accepter/tracker/turn-in-er'

https://www.curseforge.com/wow/addons/azeroth-auto-pilot-classic
azeroth auto pilot has alliance/horde // not sure if actually a GOOD guide

https://www.curseforge.com/wow/addons/allyroute
ALLIANCE ONLY level guide // actually good

https://www.wowinterface.com/downloads/info25068-DetailsDamageMeterClassic.html
lightweight feature rich meter // damage done meter > DPS meter

https://www.curseforge.com/wow/addons/atlaslootclassic
loot tables for dungeons/raids/pvp gear/itemsets/crafting

https://www.wowinterface.com/downloads/info24921-DeadlyBossMods-Classic.html
for onyxia

- fun for release -

https://www.curseforge.com/wow/addons/the-classic-race
tracks highest level top 50 players on realm // unsure if they need to have it installed, you also need to "/join world" for it to sync

https://www.curseforge.com/wow/addons/speedrunsplits
a cooler /played

-- other lists
https://docs.google.com/spreadsheets/d/1gLrmUgzzIxMExATvLdcjf60nHMwEKd4voWDTQB6JTcA/htmlview?sle=true#
https://classic.wowhead.com/news=294702/best-addons-for-wow-classic
https://www.bytesin.com/best-addons-for-classic-wow/
https://www.reddit.com/r/classicwow/comments/cpyyd2/what_addons_are_you_going_to_use_in_classic/ewsmcpn/