Your boxing yourself in with having one barrel to do all the things you want to do and I am going to recommend the Mossberg 500 pump with the two barrel set. you get a bird barrel and either/or rifled or smooth bore for slugs and buck shot.
Changing barrels is as easy as changing shoes.
Remington and NEF also make some nice offerings to fill your needs .
Please understand that these are suggestions and it's you who will make the final call on what you want.