There is no such thing.
My best shooting rifle is a nice Cooper 52 in .280 Rem.
Shotguns, well there are so many different things you use one for, that one that's best for one thing is likely not best for other things.
I duck hunted for 30+ years with a Browning Citori Field Grade, so if I had to pick one..... But really that's just the shotgun that has the most field time with me so it's got 40 some odd years of memories embedded into it's wood and steel.