Canvas is breathable but stretches less; lambskin or goatskin is softer but will mold and expand significantly to your foot over time.
Do you have a in mind (e.g., leather, canvas, tweed)?
What is your (city/state) so I can find the nearest physical shop?
Avoid water at all costs. The jute (rope) sole will absorb moisture, which can cause it to swell or unravel.