It would be more complicated than that and using a user would be of limited use.
Let’s say that you want a page separate from the user profile page to store additional user values. You could dynamically set the user where the values are save to for an options page based on the currently logged in user. Only one such page would ever be available and only the currently logged in user would be able to view or edit the values.
I haven’t got a clue what use case would involve saving values to specific term.
However, getting values from meta is generally faster than getting values from options unless you have the options set to autoload.
I generally use the last option. This allows me to keep different options for different options pages separated in the options table and allows me to have the same field names used on multiple options pages because the option_name value varies by option page.
