So many factors decide whether your shoe is comfortable!

You cannot blame a shoe brand or design if it is not fitting you well. Not always.
Even the best footwear manufacturer will make shoes with the standard foot in mind, but there are tens of factors that decide whether the shoe is perfectly suitable for your foot. Consider these:

Foot anatomy and body type: 

Your foot may not be of the perfect shape due to age, change in shape caused by misfit shoes or else.
Foot ‘anthropometry’ or proportions may differ considerably on whether you are a Chinese or a Mexican.
Feet differ a lot on the strength of the heel, the way toes and their bones are set inside the foot, slight bent of the foot towards left or right, comparative length of toes and so on. We are not even considering a malformation such as flat feet and bent toes. Infirmities can also involve ankle and leg.
A high body weight magnifies even slight foot disorders.
The way you walk matters a lot too.

External factors:

The shoe fit and comfort depends on climate too.
Feet as well as the material behave differently under different conditions of temperature and moisture.
The surface on which you walk also matters and also the duration for which you wear the shoe. Walking with high heels on gravely, spongy or very slippery surfaces is like inviting danger, but even if you are able to avoid the visible danger, it may hurt the inside of the feet because of awkward and unbalanced gait.
Even how you wear the shoe matters: too tight fit, tightly tied laces and too tightly fitting elastic may lead to bruises and bunions in addition to temporary discomfort.
The shoe size may not be exact for your feet. When you buy a tight-fitting shoe, it is also important to know that the feet are longer and plumper after a long day’s work.

Shoe itself:

Here comes the craftsmanship, design, material and science behind shoe making. Generally speaking,in this compartment reputed brands would score better than street vendors.