MVC Controllers VS Factory Method

I have asp.net MVC project customized to work for one customer only.

I need to extend the project to work with as many customers as needed.

Each customer can decide if to turn some functionality on or off (defined in DB the first time a new customer is added)

I wonder what the best approach is:

1) using a base controller that contains the basic functionality required and add a new controller (for each new customer) that extends the base controller.

2) use only one controller and build each customer with factory method pattern (each customer has its own concrete classes).

3) use only one controller that holds all the functionality and turn functionality on or off depending on DB switches (defined in DB the first time a new customer is added)

thanks