The bottom. Which I guess is the bit without the sticky out but that it’s snapped of a bunch with. You just squeeze the bottom black bit and it opens up.
Most people I see pull the top but that’s more unreliable. I believe monkeys will use my technique, or rather I’m using theirs.
Interestingly, that’s where they flower. Banana growers knock the flowers off so they can’t pollinate leaving it with the black bit on the end that’s easy to open.