That's probably because of the acid in tomatoes which makes a pretty good cleaner itself!
We have a gas burner and electric oven. I love the burner but hate the oven as it's a particularly nasty and temperamental piece of equipment. The bottom element isn't enough to get the oven really hot for bread, but the top one is too much and burns the top of everything before the bottom is cooked. Makes great roast potatoes though, if you boil them first!
If you get a reliable and glitch free electric oven, then I'd say they were best... Stove top - Gas burners give you much more control and you'll always be able to make hot water/food if the electricty goes off.