You will need a video camera / camcorder if you are not satisfied with the video quality of your smartphone or DSLR. Remember, smartphone video is compressed, so quality is an issue. On DSLR, sound quality is an issue, as these are primarily photo taking machines.
Good video cameras provide more image detail, better color, better sound, and longer battery life than run-of-the-mill video cameras.
They also have good image stabilization and less noise in low light. They have good touchscreen controls, and generous 20x optical zoom.
The best video camera: Panasonic HC-V770 HD Camcorder (comfortable to carry and sue over long periods, good video quality, stabilization, and great audio)
The second best video camera: Canon VIXIA HF R600 (less expensive, smaller, and lighter)
The third best video camera: Panasonic HC-V750K (great price)