All the advice above is good - but too, the age and condition of the shooter is of much importance - as well as individual 'tastes'. I personally find a heavy straight octagonal barrel to hold better - however many prefer swamped barrels - I must admit some heavy section swamped barrels do hold nicely - with 42" barrels and lots of meat in the breech, like the 42" (or is it 44").50 in "C" weight, ie; Taylor's virginia rifle.
Light 42" to 44" "A" weights in swamped don't hold well for me unless .40 or smaller calibre - yet while other guys think of anything over 8 pounds as being too heavy, I prefer 10 pounds of more for purely offhand shooting. Short, 32" 1 1/8" straight octagonal barrels hold particularly well in large calibres, 20 bore or much larger, but the stock design must be right for a pocket of the shoulder hold - this brings up another factory - stock shape - shoulder, joint or arm hold - all require different ergonomics in a stock - along with all the 'other' factors.
Being able to handle a variety of rifles will tell you more than suggestions here.
