For "full size," 66 is best in my opinion. Line length, ambient temperatures, wing loading, and others may affect amp draw and ESC heating. I have used the Igor's 12 x 5N and run about 10,400 and with the 11 x 5 about 10,800.
Average amp draw will be about 20 ish, but peaks significantly higher. Likely on amp values only, either will work, but most use 66.