Fit. The paramount quality of any boot, and it defiantly evades quantification on spreadsheets. So boot buyers rely on subjective reports of fit, from others whose feet are absolutely, positively different than their own.
Each manufacturer uses a unique last or foot model. The closer that last resembles your foot size and shape, the better that brand will fit. Try several on before committing. Once you find the right last/brand, you can reasonably expect future models by that brand, in your best-fitting size, to continue to fit well. At least until the last model or your feet change.