The Oracle is bag fill only, aside from being able to take a direct hit or two while the bag is filling. So that one doesn't really compare to the other two, which are direct draw/whip only. They're all efficient, but if you're looking for one that really encourages you to use less, you should look at the log vapes. The small bowls still provide satisfying hits, but require refilling, and you'll often find yourself not doing that, because you won't feel the need. The bigger hitters, like you've listed, will encourage you to load large and finish off the bowls.
Of the 3 you've listed, I'd go with the SSV (assuming you think you'll prefer whip hits to bag fill). It performs. It's reliable. And it's more affordable. If you're OK with a hands free setup, I'd also consider the Da Buddha. It only differs in the connection angle/ergonomics, and looks.