What kind of grinder is better blade or burr?

The main difference between the two types of grinder is consistency. 

Blade grinders are a great and an affordable way to get coffee ground quickly, but the grind tends to be inconsistent.

Burr grinders crush the beans at a high speed through spinning wheels (burrs) resulting in a uniform, more consistent grind. 

A uniform, even grind is important because it allows a more even extraction during brewing; resulting in better tasting coffee.