As others have said, that's a personal choice. For shotguns especially, the way it fits you and lines up from your shoulder to the front bead is so important.
A couple things to think about:
1)How does the gun "feel" for you? Does it feel natural on your shoulder or are you craning your neck to get a good sight picture?
2)Semi-autos (particularly cheaper ones) are prone to feeding issues if you use cheap ammo or if they're not maintained properly, especially in wet or cold weather - what kind of weather do you hunt in? Wet, dry, dirty, good ammo, $hitty ammo, whatever - a pump will keep on cycling and shooting forever. Plus the pump is less expensive to buy. A good new one or a really good used one can be had for a few hundred dollars less than a semi of equivalent quality.
3)Have you considered an O/U or SxS? Either of these, if you have the cash to buy a good one, will most likely suit all of your needs, feel and point better, last longer without needing parts or maintenance, clean up easier, and generally be more enjoyable in the field. They're light and fast, and classy (lol). I do concede though, that they're not always the best choice for waterfowl or turkey hunting, but for chickens and rabbits, they're just right.
Lastly, you mentioned duck hunting - make sure whatever you buy is suitable for non-toxic shot. Noticing a bulged-out barrel that was running steel through a barrel/choke that's not meant for it can really ruin your day.
Single-shots are a good thing to start with, but when you're grouse hunting, you'll be glad for that quick follow-up shot when you miss or when there's another one that pops up out of the high grass and you didn't realize it was there.
