Neither.

The one on the right runs a significantly non-trivial chance of a rolled ankle.

The one on the left is purely slip-in, with no way to use the toes to anchor the flip-flop onto the foot.

I’m taking right/yellow. Thankfully those sandals have a little loft while she’s bent over like that so she’s perfectly positioned for a drink from the fire hose!

Green

Left

Yellow

If one is just considering sandals yellow is better. However, for everything else green is nicer. Not to say yellow isn’t nice of course.

Yellow

Removed by mod

Going green, but that’s a tough one