Some chassis kits have elaborate movement methods, legs, tank tracks, and tri-star wheels, to name a few. While these are fun and I encourage experimenting with them, this is not the place to start at. So, I recommend a thoroughly sensible, if basic, wheels on motors version.

There are kits with four-wheel drive and six-wheel drive. These can be quite powerful and will require larger motor controllers. They may also chew through batteries, and you are increasingly the likelihood of overloading something. This also makes for trickier wiring, as seen in the following:

Two-wheel drive is the simplest to wire in. It usually requires a third wheel for balance. This can be a castor wheel, roller ball, or just a Teflon sled for tiny robots. Two wheels are also the easiest to steer, avoiding some friction issues seen with robots using four or more wheels.

Two wheels won't have the pulling power of four or six-wheel drive, but they are simple and will work. They are also less expensive: