I remember a while back, reading someone had measured the electrical useage of a couple of laptops and desktops when on sleep, compared to running a couple of apps. I remember the Dell (I had one at that time) on sleep used something like 1/40 of the juice that it did when it was on and running with light useage. From that point onward, I've used sleep/standby as the usual method.
If by "better" you mean, "What uses less juice," then of course turning it off would be better. If you meant, "What would only use little to no juice, but still be very quick to display," then it would be sleep.