I can't believe that 6s and 7 1/2 have the same amount of votes. I have killed pen raised birds with 7 1/2 trap loads but I would think on wild birds you would want a bigger shot size.
alot of guys that hunt areas that have both pheasant and quail like the 7.5s or 6s.
Believe it or not, 3" 20ga 1.25oz 7-1/2 is one of my favorite 20 ga loadings. Killed lots of birds with those.
Here's an interesting comparison between a #5 (lead) and #7.5.
#5 shell is .120 in diameter; #7.5 is .095 - not much difference.
#5 shell (1.25oz.) has 212 pellets; #7.5 (1.25) has 437. For some reason more pellets in the pattern seem to work better for me...