Since you posted this in the Audio Editing catagory, I assume you are talking about music waveforms. The current audio waveform view used by all audio editors is actually a very high resolution bar graph, with one bar for every sample (44 thousand per second or more). Newer software such as Steinberg's Wavelab can augment this graph with color to give the editor an idea of not only the volume of the recorded sounds, but the frequencies involved.
line graph
A scatter graph.
A circle graph is best used when the things being measured are a part of a whole. For example, a business that is analyzing department costs against total costs. Each cost is a percentage of the circle.
a circle graph is the best graph to use for that!!
a bar graph is best used for comparing amounts, a line graph best represents a steadily increasing value. For example prices of a shirt (line graph), or viscosity of liquids (bar graph).
The best graph for numerical information will depend on what you want to present. The linear graph, bar and the pie graph are some of the best graphs to present numerical data.
Bar graph
line graph
which of these is best shown on a bar graph?
the best graph to use to represent fractions is a pie graph, that is if all the fractions denominators are the same...
pie graph
a line graph will join all of the points yet a best fit graph will only join the dots which follow the pattern.