A sway bar, or anti-sway bar reduces body roll but has a detrimental effect on flex since it basically ties both sides of your suspension together. A stock anti-sway bar with longer links should be adequate for most purposes.
A panhard bar, or track bar, is a bar that goes between the frame on one side of the chassis to the axle on the other. It is used in link based suspensions with solid axles as a way to keep the axle from walking back and forth. It can also be used on spring based suspension systems to reduce steering issues.
A traction bar, or anti-wrap bar, is used on spring based rear suspensions to stop the axle from wrapping up under high torque loads, such as take-offs and hill climbs. This stops you from s-curving your softer, longer rear springs.