In terms of set-up, a good-quality aux cord takes you less than a second to start streaming music into the device of your choice. With Bluetooth, it can be a hassle to set up. Additionally, not every device is Bluetooth-friendly and you run into the risk of the connection wearing off beyond certain distances. Plus, it may not work for long drives as certain devices automatically cut connections after a certain amount of time or due to your phone dying. With an aux cord, sometimes it allows you to charge and stream your playlist at the same time — which is a great feature for those trying to avoid a quiet road trip. At the end of the day, it depends on the devices you have and their compatibilities.