Should I award contract to the cheapest or most expensive quote?

Neither. Try to get 2-4 quotes. The standard is to throw out the highest and the lowest and group the middle ones and compare. Sometimes, the highest quote will be a more extensive, complete quote that includes more crafts than the cheapest or even the quotes lying in the middle of the price range. So, go over every quote, studying and listing the differences in everything included and the prices between them.