Just going by the brass scattered around at the ranges here, .223 is by FAR the most popular, followed by 7.62x39 then 308. Pretty much tied after that are 30-06, 270, 30-30, 303, 7mm RM and 300 WM.
The folks I hunt with primarily use the boring ol '06, but there're a few guys with 7mm's. One fellow uses a 375 for everything