Sliding gates require less room for you to open them than the swinging ones do. A swinging version will require you to leave enough space in front of and behind the panel for it to swing open. It will swing out the same amount that it is long so you must mark out how much property you need to reserve for this. In areas where the space is limited this can be quite inconvenient. Sliding gates slide beside the fence that is there so it only requires a few inches more of space to allow a clearance between the enclosure materials and the sliding gates.
Swinging gates often become warped and drag across the ground when you are attempting to open them. This is especially true if someone plays on the item and rides it while it is being swung to and fro. Sliding gates have wheels on the bottom touching the ground so they cannot be warped as easily as the swinger. Most people do not want to try and ride on the slider like they do on the swinging version.
If you have security issues on the property that is being protected by the fencing then the slider will provide you with a greater amount of security than the traditional version. This is in part due to the way that they are attached to the material enclosing the area. The traditional versions of these items are attached by hinges on a post. People can either remove the hinge pins that are securing the panel to the hinge, or they can unscrew the entire hinge and swing the panel open enough to enter. The sliders are not attached in this manner and are more difficult to remove.
If you want to have an automated system for opening the gate then the slider is the correct choice. They are easier to activate remotely and can be connected to security fencing that is electrically charged. They are also easier to slide open a small amount for a person to enter without letting an animal gets out. So enclosures with guard dogs benefit from having these items installed rather than the traditional swinging panel.