Returning unique_ptr or just moving object?

Question

I have a factory that is creating objects, but I'm unsure what the best way is to return these objects. I have the option to return a unique_ptr<Trigger> , or I could just return Trigger that is handled by a Move constructor. What is better practice? My best guess is Move because you are guaranteed an object.

class TriggerFactory
{
public:
    TriggerFactory();
    ~TriggerFactory();

    Trigger createMyTrigger() const; // Trigger contains a move constructor
};

vs

class TriggerFactory
{
public:
    TriggerFactory();
    ~TriggerFactory();

    unique_ptr<Trigger> createMyTrigger() const;
};

Answer 1

Frequently the Factory pattern is used for polymorphism: the Factory will return a specific concrete type of some abstract type. In this case it must return a pointer to a heap-allocated instance (else the return value will get sliced).