I have a hard time understanding how a toaster oven could be more efficient than a microwave. A microwave heats the food directly, vs a toaster oven which (like a regular oven) heats air, which then heats the food... If there's a resource that demonstrates a toaster oven being superior, I'd love to read it.
We have a small convection oven that we love. Perfect for things that don't work well in the microwave and definitely uses less power than firing up the large oven. Can be used in place of a large oven for everything that will physically fit (note that a lot of packaged food says do NOT use in a toaster oven, but is OK in our small convection oven).