Ranking The Big Opening Moves

From Yang Yilun's Fundamental Principles of Go

Class One

Play in an empty corner

Class Two

1. Approach/enclose a 3-4, 5-3, or 5-4 corner
2. Play the midpoint of a side where there are 2 shimaris optimally facing each other. This is called "good development potential". The other "good development potential" is a 4-4 stone, which also has the urge to extend a midpoint. The colors involved in good development potential do not matter (so much).
3. Start a fight (joseki) in a corner

Class Three

1. Play the midpoint of a side where one player (either) has good development potential
2. Make an extension which simultaneously strengthens you and weakens your opponent
3. Approach/enclose a 3-3 corner
4. Approach/enclose a 4-4 corner

Class Four

1. Play midpoint where neither side has good development potential
2. Make a 3rd enclosure move in a 4-4 corner or reduce an enclosed 4-4 stone corner
3. Make any remaining 2 or 3-space extension

Notes

All moves of the same class are equally important and "bigness" comes into play if only moves of the same class are available.

Shuko gives a slightly different ranking in Reducing Territorial Frameworks:
1) empty corners
2) enclosures / approaches (equal value)
3) extensions
4) checking extensions (tsume)
5) jumps / erasures (keshi) (equal value)