Best fruits
1) Blackberries 
1) Mandarins
3) Green Apples
4) Mango
5) Oranges

(Tie for first, assume all are home-grown, wild, etc)

Mandarins are the best designed fruit. 

Outer shell for protection. Fun to open. Not easy to squish. 
Can split without a knife.
Goes well with kotatsu.
Delicious citrus.

Just wanted to try something on MidJourney while reading your post so here you go - a worthless piece of design :)

On-chain creative + graphic designer with extensive experience in advertising.

Vilnius, Vilnius City Municipality, Lithuania

If an apple didn't have seeds, I might be inclined to agree . Maybe your variety of mandarins are stickier than ours 😉

As for bananas, I think I personally value  the easy shareability of mandarins, though the fast peeling of bananas is a huge benefit.

That's true if we're talking about citrus fruit. 
I wouldn't agree about being easy and fun to open - usually you have sticky hands afterwards. I would vote for the good old apple as the best designed - no need for peeling, just wash and eat.

for real, they're the most fun to open...and i can eat a thousand.