‘Aimer bien‘ means you are actually emphasising that you like (not love) something.

So in order:

1. (Strongest): Adorer
2. Aimer (can mean love or like)
3. Aimer bien (like)

Objects

If I want to say that I really like an object, I will use “adorer”:

J’adore mon ordinateur, il est très puissant !

If I want to simply say that I like an object, I will use “aimer”:

J’aime ma nouvelle étagère. Elle est pratique.

If I want to say that I globally like an object, I will just use “bien aimer”:

Ce tapis n’est pas si mal. Je l’aime bien.

So for objects, the ranking would be the following for me:

1. Adorer
2. Aimer
3. Bien aimer

People

“Adorer” and “bien aimer” will work the same in a sentence for people. “Aimer” is trickier, depending on the context and who you are talking about. It can either mean that you simply like someone or that you love that person. So it can be both less or more powerful than “adorer”.

If we are talking about a friend of us that I just casually like, I could say:

J’aime Benjamin, c’est quelqu’un de sympa.

Although if I am talking about my girlfriend, I would obviously say:

J’aime ma petite amie.

Now, to be really honest, I think if I was referring to a person who is not my girlfriend, I would either go for “adorer” if I really like this person or “bien aimer” if it’s a friend with whom I’m not sharing strong links or that I don’t admire. But it still may be possible to hear someone just say “aimer” for a person.

The final ranking for me would then be:

1. Aimer (in the context of love)
2. Adorer
3. Aimer (in any other context)
4. Bien aimer