Every well-equipped kitchen has either an electric, gas, or dual fuel oven with an integral cooktop. Of these, electric models are usually a little less expensive and installing them does not require connection of a gas line.
Oven options are rather limited. Models with a self-cleaning feature are usually a little more energy efficient because they are better insulated. Although they use intense heat during cleaning, they also require less energy to cook your food. If you clean your oven only two or three times a year, you will likely save energy by buying a self-cleaning unit instead of an equivalent, regular oven.
The other common option is the convection feature that cooks by circulating hot air about the food use only one-third as much energy to operate as conventional ovens. They produce further savings through reduced cooking times because the food is more evenly exposed to heat.