What would be better to add Unit test to: Manager, controller, DAL?

we have an architecture with Controller, Manager (for BL) and a Data Access Layer

Where would it be better to add our Unit Testing. Something tells me that the manager is the best place, because logic will be stored there.

Another idea is that if we test the controller it's more complete (but it sounds too wide in some cases a lot of functionallity would be tested )

And the DAL sounds like THE most atomic part to test, but we are not testing the real outcome. BR

MG