Maverick is just a copy of the Mossburg 500. I would go with 12ga unless you have arthritis problems or something cause parts are more available (such as that extra barrel). Probably better to go with short barrel as home defense and buy the extra hunting barrel that sometimes comes with the chokes. It all depends on WHAT you are hunting. Personally I don't hunt much anymore, but have declared war on turkeys. For something that can see a grasshopper at 100yards I had a close encounter with a huge tom that ran out in front of my car and tried to take flight. 1. didn't know they could run that fast 2. caused a violent encounter that cost $208 to replace the windshield and flew away, leaving me with 8 feather souveniers 3. Bad for them, good for me, they taste great...so I've resigned to eat them every chance I get...LOL
How about I just get this with the 18.5" smooth barrel?
Mossberg & Sons | 31017
Depends on what you want to hunt. Hunting Quail over dogs working close in; a short 22 - 24 inch barrel lets the gun move much quicker. On the other end is high flying Geese; a good 28" plus barrel.
Most hunting shotguns fall in the 26 inch and 28 inch range as all around guns. These do many things well but excel in no one area. I have owned pumps and over and unders in a number of lengths and gauges over the years. My personal preference is an over and under in 20 gauge with 26" barrels. Light enough to carry all day, good enough to bring down most field birds and all small game without issue. Choke it wide and double ought buck, it's a deer gun.
Everyone has there likes and dislikes. Buy the best quality you can afford. A Remington 870 Express combo is a great choice for just a few more dollars than what you are looking to spend and will likely last a lifetime. That was my choice for over 10 years due to flexibility and affordability.
Others have stated though that it would be cheaper in the long run to get the longer hunting barrel first and then get the 18.5in HD barrel later.