There is no definitive answer to this question as it depends on what you plan to use the binoculars for. If you need binoculars for long-distance viewing, then 12x50 binoculars would be a better option as they have a higher magnification. However, if you don't need such high magnification and would prefer a lighter pair of binoculars, then 10x42 binoculars might be a better choice. Ultimately, it's up to you to decide which features are most important to you and choose the binoculars that best suit your needs.