Addons that give you an advantage in a pvp or pve enviroment are imo bad.
If these addons are QoL changes then they should be implemented in the game itself
- better custom UI
- bag addons
- mail addons
- better interfacemenu for mounts and pets etc
- swapping gear
Things like that. Bossmods should be in the game itself (which it now sorta is in a weak way)