What factors should be prioritized when choosing the best bike lights for safety, and are there any significant differences in functionality and visibility between high-end and budget options that would justify the additional cost for urban commuting in low-light conditions, or is the added expense primarily driven by features that are more relevant to competitive or off-road cycling? Are there any industry standards or certifications that can be used to compare the brightness, beam patterns, and durability of different bike lights, and how do these factors impact the overall effectiveness of the lights in enhancing visibility and reducing the risk of accidents?