Answer
Percents are typically easier to work with because they imply "out of 100" (in other words the common denominator is always 100).
Work Step by Step
While fractions, decimals, and percents are all used routinely world wide, it is often true that humans prefer to work with percents. The reason is that percent ("per-cent") means "out of 100". This makes the number easy to understand. For instance, saying "12 percent" means "12 out of 100".
On the other hand, fractions can be less intuitive. For instance, it is hard to understand what $2\frac{3}{8}$ means as a fraction of something. Similarly, in decimal form, 1.28 is less intuitive than 128%.
