tripods serve to stabilize your camera in various conditions.
Light ones are good because they are easy to carry around and, barring any wind and vibrations, are just as stables as a heavy one.
The heavy ones are less prone to vibrate in wind and less receptive to vibration. They have more dampening built in. The very expensive ones are made of special compounds of minerals and lava-rock etc.
The heavy ones are also better able to support heavy gear, such as large bodies and lenses with brackets on and maybe even flashes. But they can be very expensive and cumbersome to move around in rough terrain.
The leveling help you if you are - for example - on an incline. A small hill maybe. It will assist you in getting the horizons straight, for example.
The one that is best for you, depends entirely on the trade-offs you are willing to engage in. Some have both for different situations.
Good luck with your choice!