* Fácil: This is the most common and direct opposite, meaning "easy."
* Simple: This emphasizes the lack of complexity.
* Sencillo: Similar to "simple," but with a connotation of being straightforward and unpretentious.
* Ligero: This means "light" and can be used when something is not burdensome or demanding.
* Agradable: This implies something is pleasant and enjoyable, making it the opposite of difficult in a more subjective sense.
The best word to use will depend on the specific situation and what you want to emphasize.