A gas oven is the better choice for roasting. Heated by a flame that is powered by natural gas, the temperature can fluctuate slightly, making baking a game of guesswork. It is hard to bake a prefect batch of cookies when the heat in the oven can be slightly different with each cookie sheet you slide onto a rack. Electric ovens are much better at baking because their heat is even and steady. They aren't so good at roasting or broiling and can produce meat that is a little on the dry side if you cook it at too high a temperature. Of course the optimal choice is to have both in your kitchen, a gas stove for roasting leg of lamb and an electric stove for baking pastries.
Often the decision of which type of oven to buy is really made based on what type of stove you prefer. If you are purchasing a range that includes the stove, you have to take the burner into account when deciding what to purchase. When it comes to stoves, gas ranges provide a heat that is much easier to control. When you turn the burner down, the flame receded causing the heat in the pan to immediately drop. When you turn down the burner on an electric stove, the temperature of the burner has to drop naturally before the temperature in the pan can go down. It is very easy to over cook food on an electric stove, and takes a bit of getting used to before you can time things to perfection.
When it comes to savings, electric ovens tend to be a little more expensive to run than gas ovens. It costs more per minute to pay for the electricity to run and electric oven than it does for the gas to run a gas oven. It even costs more to run a microwave than it does to run a gas oven. While the cost of running an electric oven is more, if you were to comparison shop for a gas oven and an electric oven that were of similar capacity, the gas oven would probably cost you more.
As far as safety is concerned, either oven should be safe, although with gas ovens there is always a risk of a leak While this is possible, it is highly unlikely.
When it comes right down to it, there really isn't an answer for the question which oven is better, gas or electric. The truth is that the answer to which oven you should own is a highly individual one that has to take into account your cooking style, price range, and of course the most important factor, what type of hookup your kitchen has.