Whats the best hight yealding strain?

What is the best indoor strain to grow to get the higest yield? Im looking for something that is easy to grow as only got a couple of grows under my belt so far. im growing in a cold loft using 400watt HPS, would you also say upgrading to 600watt would maka a massive diff?

big bud is supposed to have a high yield

cool, i was told LSD was good so got them growing now but not sure what ill get off them.