I'm trying to go for highest overall efficiency. For my setup, about 7.5 gallons combined volume in the mash/sparge is ideal (gives me about 6.5 gallon boil volume, and somewhere around 5.25 final).
In any case, I'm trying to figure if 12 pounds of grain plus 4 gallons of water (1.33 qt/lb) in the mash plus 3.5 gallons sparge is the ideal path, or if 11 pounds grain and 3.5 gallons water (~1.27qt/lb) in the mash plus 4 gallons sparge is the way to go.
Ultimately, max efficiency is the goal, but there's also something to be said about a higher concentration of grain-derived fermentables in the mash. If you were in this position, which route would you go?