Each of these equations provide different things. The standard form  equation is used to mostly to transfer the slope intercept form to standard form.That in which provides a clearer understanding of the concept trying to get across.While on the other hand the Slope intercept form is used to contribute to finding  the slope of the line. when doing that you will use the equation that states y=mx+b. Point-slope form is another kind of linear equations. The point slope form provides a variety of things like the points the line goes through and also the equation of the straight line. 
The information that is provided for each equation form changes your strategy for graphing because if you say for instance your solving a slope intercept form equation and you have only the x and the m you would have to go all the way through the process to find the b then you would be able to graph your equation.I find the point slope more valuable to the setting including a standard form because of you would have to find the slope and all of that before you begin to work but with it would be in plain sight normally.