Unripe vs. Ripe bananas: Which to Choose?
Normally we choose bananas simply on the basis of their look to us. If they appear ‘pretty’ enough, we put them into our shopping bag. As bananas are very popular among all kinds of people, especially dieters, parents of young kids, students and office workers because they are tasty, filling, highly nutritious and easy to get, carry around and eat.

Ripe bananas
Pros:

Cons:
However, late stages of ripening naturally lead to loss of some useful nutrients in the fruit. Also, high sugar levels make such bananas undesirable for people suffering from Type 2 Diabetes.Unripe bananas
Pros:

Cons:
At the same time, unripe bananas’ high resistant starch levels are known to cause gas and bloating in some cases. Also, they have not that high level of antioxidants, so, if one is interested in this particular factor, yellow banana is the way to go with. So, there are no any essential restrictions regarding this or that type of bananas, except for sugar level diabetics should take into consideration. But there is also the point after which bananas become overripe. These are of no any benefits to a person, so it is necessary to not let them spoil. For that reason, ripe bananas are recommended to be stored in a fridge to prevent loss of useful elements, and fruit with brown patches is better to be eaten as soon as possible. Moreover, despite all the pros and cons that have been introduced here, there is always some kind of an interim state in bananas’ ripening process. Remember that fruit that doesn’t seem neither that green, not that yellow?While there is no solid scientific proof to this, but we can still suppose that such bananas can give us at least some of the benefits of either ripe or unripe kind that are listed above.
References:
STUDIES ON THE BANANA.-I. – Journal of Biological Chenistry
Comparative Study of Ripe and Unripe Banana Flour during Storage – Journal of Food Processing & Technology
Green Bananas: Good or Bad? – Healthline.com