Mossberg 500 shotgun- upgrade or buy another gun
But I know what you mean about a certain gun being your all around gun. The remington 870 was my first gun and Ive got a strong affinity for the 870. But if you can afford it then start diversifying. A shotgun on small game is overkill plus youll be chewing on lead BBs. A shotgun slug on deer bruises and ruins a lot of meat. Like a previus poster said, coyote hunting can be with almost anything you like, dont worry about diversifying there unless you really get into the sport and start killing more than a few coyotes every year.
That should be plenty for what I need. I also foresee an AR in my near future, but that depends on if my buddy ends up selling his
Just use 'big game' bullets in the 243, does just fine.
IMO deer hunting without any sights on a shotgun is one very small step above being unethical. You don't point a slug you aim it and you can't do that with a bead. You could go with a rifled slug barrel but I would MUCH rather have a rifle than a slug gun for more range, better accuracy and more power. Most people don't really need a special coyote rifle as 95%+ of coyote hunters in this state don't shoot more than 1 or 2 per year, just buy a nice deer rifle in 308, 270, 30/06, etc and use it for coyotes also. Pelts are worth next to nothing so why worry about what the bullet does to the pelt?
I would also pick up a 22 as they're great fun to shoot cheap ammo with and if you like squrell hunting a 22 makes it into hunting vs shooting with a 12 gauge.