Are you the kind of person who eats bananas with a blotchy brown skin? According to this piece, that's is the best one to eat - no 7 in the picture. Only ripe bananas have broken down resistant starches into sugars.
When a banana is picked for the grocery store, it is picked and shipped green (unripe). In this stage the banana is comprised of a type of resistant starch for which the human body lacks the enzyme to break down. This banana (#1-5) will plug you up. Plus it has that awful “dry” texture that makes you want to spit it out.
I'd go for no 7 too - possibly no 6 but that's it. A banana should taste like a banana.