In order to decide which theory is the best we need to know The starting point, The ease of journey and the final destination. And of course if you compare all the theories, you will find the truth that Divine Love (Devotion) is the best from all accounts! And it does not mean other theories will not take you to the divine realm of infinite happiness! One should be able to distinguish between quantity and quality!
Compare the following happiness situations:
1. You get to see mango and you are happy to see its beautiful shape and color.
2. You get to see mango and you are happy to see its beautiful shape and color + you get to know its fragrance and you add another attribute the earlier happiness.
3. You get to see mango and you are happy to see its beautiful shape and color + you get to know its fragrance and you add another attribute the earlier happiness + you get to eat the mango. Thus you add yet another attribute to the happiness

The same kind of distinction is there in
1. Gyan : (I am God) : Seeing Mango
2. Yoga : Seeing and getting fragrance of Mango
3. Devotion : Seeing and getting fragrance plus taste of Mango