I think that Mangoes are "best" when picked fully ripe from the tree as most fruits are. And like Bill, I will also offer that they are generally horrible when picked green and ripen "in-transit" or while waiting to be sold. Sometimes you get lucky. However, IMHO Mangoes are very good to excellent tasting when picked after coloring and/or ripening starts but definitely before they are fully ripe. And for most, that is also the most practical option.
Each season, my family and I personally pick ready now, ready in few days, and ready later Mangoes from South Florida backyard neighborhood trees to being back to North Florida to eat, share, and freeze. I shared a few of this year's Hadens - that were picked less than fully ripe - with neighbors and friends (a couple on this forum). Everyone said that the mangoes were delicious. I concur. So with care in selecting the mangoes - not just wholesale distribution - picking Mangoes early is actually ideal, practical, and very tasty practice.
Finally, I have tried unsuccessfully for two years grow a mango tree here in 8B. I need a 20ft tall green house to make it work and that just isn't going to happen.