PS- the only time I've had a deer drop with a 12ga slug was a doe/button buck at 75yds I think, and a buck I spined at 20yds, I once put 5 rounds in the heart of a buck at like 40yds that just stood there...
These guys who say they love/prefer 12gauges make me laugh, to each their own though, but for deer, I see no reason for a 12 ga over a 20ga.