Most importantly is providing enough light for the space you plan to use within budget, then worry about efficiencies.
IE if I've got a 4x4' space, I'd rather have a 600w hps than 200w of high end led lighting. Electrical costs are minimal compared to final product value. But cutting watts and maintaining the same yield will pay off in electrical savings eventually. (200w is $17/month at 24/0 lighting. 600w is only $52/month. A 7g yield has the value of 600w of electricity all month)