What are the main abstract classes used in ax 2012 for ex: runbasebatch, sysoperationcontroller
You didn't get any answer because there is no good answer. What is a "main" class depends on what you need. What's super-important on one project may be completely irrelevant on another.
Also, why are you interested only in abstract classes and not non-abstract classes or interfaces? Shouldn't you focus on business logic rather than implementation details? For instance, if SysOperationController is implemented as a concrete class and not an abstract one, it's functionality and purpose is still the same - so it doesn't really matter.
I think you should start by explaining what problem you're trying to solve.
Also note that it's possible to generate a list of all abstract classes - then you can choose which are the main ones for you.