Which base class to inherit if it's a common class in odoo9
If you are going to create odoo normal module then you must create models.Model.
If you are going to create odoo module which will handle post or get request from web service then you must use controller.
If you are going to create odoo module for other module, and this module is wizard then you must use transient model and etc.
Also if you need you can make simple class and use in your module but with your question I cant tell you more
I'm using odoo9 for my project.
In my project, there is a common excel handling class fill in the excel template and output result, and here is my question: which base class should it inherit? models.Model or http.Controller, or nothing?