X2 I have a friend with an 1187 slug gun 20ga and it's just deadly accurate.
I too have an Ithaca M37 with a rifled M87, 20 inch barrel.
There is certainly an advantage to the 20 VS 12 gauge, for more range during deer hunting season.
But this often comes at an added $$$. Any decent 20 gauge sabots, often have really stellar performance and a flatter trajectory. These are factory sabots with a definite 'aim' of providing a superior deer stopping calibre.
If one really cares not of the cash cost, these premium rounds and say a Savage or Browning rifled bolt action shotgun are the cat's meow.
So top quality is married to a very specialized rifled shotgun/bolt action/hinge action. These often are popular in shotgun only jurisdictions, with those that can afford them & the costly ammo, that is.
A short barrelled rifle, for most hunters is a better option for those who have a legal choice. There are tons more ammunition capabilities. With the big plus of a longer effective range.
(cast vs copper jacketed, reloads vs factory, premium vs plain vanilla bullets)
As mentioned previously by others, those set up for scout rifle concept, with a forward mounted fixed scope. This may be the best 'pick of the litter' for your specific hunting conditions.
A close second would be any good carbine, with a conventionally mounted, varible optical sight.
Just my opinion......