Everyone wants to give advice as to what gun to use, but rarely does anyone ask how you will be hunting. I bet I've honestly owned at least 15 different slug guns and I can give you what I think are the pros and cons of the styles of guns that I've owned.
First, decide how you will want to hunt. Tree stand, deer drives, walking, ground blind, etc. That may or may not be a factor in what gun you buy. For example, I would not want a savage 220 on a deer drive. They are accurate but the bolt can be sticky and you have to work the bolt with authority. I've owned two and got rid of both. They are great for long range shots off a rest but for a second follow up shot that is quick and efficient, I would want something else.
If you go with a muzzleloader which is another poor choice in my opinion for walking or stalking, you only have one shot so you need to make it count. Plus, if you don't end up taking a shot at an animal you either have to discharge it and then basically clean it that night (muzzleloader powders can rust your gun if you don't clean it quickly and thoroughly) or figure out a way to make it safe. You will still need to get the powder and projectile out of it when you store it away.
If you decide to go with a inertia based semi auto like the benelli mentioned, you need to be careful of how heavy of a scope you decide to use. For example, I owned an M2 in 20 gauge. The weight of the scope made the gun into a single shot...it wouldn't cycle reliably with 2 3/4" shells. I had to move up to 3" for the gun to cycle reliably which increases felt recoil of the gun. I contacted Benelli about this and they confirmed that scope weight may be a factor in how the semi auto gun cycles reliably or not.
If you go with a gas operated semi auto, weight can be a factor. I've owned a Remington 11-87 super mag and a Winchester Sx2, both with rifled slug barrels and they were heavy to lug around. Fine for a seated hunt, but walking with those guns was a pain.
Pump action guns like the 870 can be heavy on the recoil, especially for new shooters who have never shot a slug before. It's not like shooting 7/8 oz trap loads.
There are pros and cons of every type of gun out there. You are smart for asking questions, but take your time on your purchase. Shotgunworld.com has a section for slug gun shooting that has a lot of answers.