The first knot most climbers learn is the "Retraced Figure Eight" knot. While a minority of climbers choose to connect the rope to their harness with a double bowline knot most of the climbing guides and instructors I have met greatly prefer to the more easily recognizable Figure Eight. Since there are a few ways to create a retraced Figure of Eight there is only one way that is becoming more known as "ideal". When all these points are met I refer to this as the "Optimized" Figure Eight Knot.
Only the amount of rope needed to create the knot is used
The loop that has captured the harness tie-in point is no larger then the belay loop
All the strands are parallel with no cross overs
After all four strands exiting the knot are "dressed & stressed" there is only 6 inches of tail
The load strand entering the knot ends up on the "inside" of the knot
Your partner checks your knot before you start climbing