Whoever wins the election, Labour or Conservative, they will have very little control of the economy. Power was handed over to the free markets in the 1980s and will never return to the Government.
At the most, the Government can tinker around the edges, but whether we encounter boom or bust is out of their hands. Global forces, which Whitehall cannot contain or influence will shape our future. The boom under Blair was not due to anything they did, the rest of the world was booming. The Crash of 2008 was not their fault, it was worldwide. The years of Stagnation under the coalition have been replicated in other western countries.
Labour and Conservative may promise a prosperous future under their stewardship, but really they do not know. Whatever they plan, the economy will march to a different tune. Deflation, an oil war, EuroZone crisis, another crash, there are thousands of things, beyond their control, that will knock them off course.