I am unforgivably obsessed with Melissa shoes so I realize this is going to be biased. But I am genuinely impressed with how comfortable they make wearing plastic/rubber style shoes.
The interior lining is is soft but firm so your skin doesn't stick to the plastic (a thing that happens with old jelly/flexi-plastic shoes).
The soles are cushioned and the straps/buckle - while being a little stiff at first - form to your foot easily. Sizing wise, because I am a 7.5, I went down to a 7 this time around* and they're really comfortable. Very roomy on the inside and kind for all the walking throughout the day. Would recommend wearing with socks if you can because plastic shoes- in my experience- tend to be stiff the first few wears.
* For context: I had purchased shoes from Melissa before, two pairs of jelly sandals, which were so adorable. Being a 7.5, I chose to go a size 8 rather than a 7. It took a couple of months for me to realize that my foot measurements are on the slighter side (narrow feet, longer toes, high arches) so I should have gone smaller.