When linear relations are described as a graph the intercepts of the graph can be easily identified. It is also easy to determine the general slope of the graph, i.e. whether it is positive or negative. Though to determine the exact slope of the graph, most often the equation is easier to work with.
It is also easier to work with an equation as all the information that a graph can provide is accessible without having to actually plot the graph. That does take a little more time and effort.
The choice between using the equation or the graph is more to do with what information needs to be collected. It would difficult to say that one of them is better than the other.