I'm a veterinary nurse and spend all day on my feet and I wear slip on black leather Hush Puppies. They're really comfy. Before that I had some clogs (don't know if you're allowed to wear clogs) with like, an ergonomic design, that were also really comfy and lasted for ages. I think they were from Grahame Gardner (a place that does all kinds of uniforms and stuff).
Hope this helps xx