Which is better Grade 5 or Grade 8 bolts?

When it comes to choosing between Grade 5 and Grade 8 bolts, what are the key factors that one should consider? Is the strength of the bolt the only determining factor, or are there other characteristics such as durability, corrosion resistance, and suitability for specific applications that also play a role? How do the two grades compare in terms of their overall performance and which one is typically more preferred for heavy-duty applications?