Alow inflation rate is preferred because

If there is a high inflation rate, then our economies prices would plummet a great amount. The cost of an object can go from $5 to $50 in an instant, and nothing would be affordable anymore. Because no one can buy things, suppliers would run out of business and go bankrupt. People who cannot get things, will start going under loans, and still not be able to afford basic needs. 

A low inflation rate is much better, because our economy is growing and expanding, to financially keep up with other countries in the world- we need to become more expensive and valuable with our currency, but still maintain reasonable rates for our citizens as well.