How SHOULD settings be saved between characters, accounts, etc?

[DewiMorgan]

Extensions save data using arbitrary methods, either not telling the user which they're using (global per ESO account? Global per windows account? Per character?), or requiring users to learn a whole new system of cross-character saving and settings-transfer or profile-definition and maintenance for each addon.

I've seen no perfect solutions to the problem, but I suspect that's because it's not perfectly-solvable. I can't imagine what a perfect solution would even look like.

Are there at least any widely-used settings-management addons, so I can at least use a system that my users might already be familiar?