War Eagle. Anywhere from a 17' to 20'. I have a 17' with a 40HP Merc. Handles most anything I run into. It's for sale (after duck season) PMG if your interested.
I have a Beavertail 1754 with a 35hp surface drive (stock). I like how well the boat is built, I bought a package that came with boat, motor, blind, seats, front lights, interior lights, bilage pump and trailer. I like how fast and easy the set up of the blind is but you need to stubble it. while hunting in Oct. I had 2 people, 1 small lab at 90 some pounds :) . 100 + decoys and all the other gear and blind we reached a blazing 17 mph. 2 weeks ago just me with blind still on boat, no decoys was getting 22 mph. I looked at many boats before I bought one and liked the fact there were hardly any sharp edges. this is a all welded boat and it is heavy. You can order the boat any way you would like from beavertail. now for the trouble I have had. 1 broken power trim mount but this was after I was trimming down the motor on top of a 8 ft log I could not see and lifted the rear of the boat up (did not see any of this) once the prop hit the log it flip the log out of the water and I had a busted mount, it was replace at no cost. Good luck in your search for a duck boat.
Beavertail or war eagle if they are in your range. Lowe makes a good hull and is far cheaper in price. As fas as motors go, it depends on where you hunt. Open water or lakes without a lot of debris you can use an outboard. Rivers, marshes, or lakes with shallow muddy area require a mud motor. Long tails are, IMHO, best for areas with lots do really shallow areas and really muddy areas. The hyperdrives are better if you have lots of submerged logs although they will get most places a long tail will.
Remember Craigslist can be your friend. You don't have to go with a custom built duck boat. You can find a Jon boat hull on CL and with a little work you can turn it into a fine duck boat. I have done this and get great satisfaction out of doing so. I look for a flat bottom wide hull no less than 16 foot. You can find a hull that has as much or as little as you want to pay for. Some are fully wired and have live bait wells and others have nothing but a hull. As long as you find a good, stable hull that does not leak you can build what you want and then put the real money in the motor.
I hunted yesterday with a friend who found a great deal on a fully equiped 17' or so Lowe. His boat has a modern 4-stroke 50hp Evinrude, boat blind (though we hunted from shore), it was camo with a big light mounted on the bow, built in seats and storage. It was roomier than my boat with room to walk around. That motor was so smooth and quiet, it was like running an electric motor. I was quite impressed.
Erik, please post a pic or two of that Mallard you built. My boat is great, but there are some very good "honey holes" that have a very tight shallow entrance, then it deepens to two-three feet in the pond area. You could walk in, but the dog would be standing in ice water in the cattails. I'm basically looking for a towable, floating shooting platform for two guys and a dog. We would tow it up river to our spot empty, or maybe with some decoys to give it some weight and stability, then transfer guns, shells, lunch and dog to walk it across the shallows into the pond, set up and shoot from a hide in the cattails.
One more thing for the OP, there is a wonderful forum dedicated to duck boats of all kinds called duckboats.net . It is very much like our forum with strong opinions on all subjects, but it was a wealth of great information for me as I went through the same process as you some years ago.
Depends entirely on where and how you hunt. I have a South Bay and it's nice in the backwater but I wouldn't take it in the open river on a bet. Just too flat and low profile. It's rated for 9.9 BTW George.
Pupknuckle with the 2072 hunts just down from me but in an entirely different manner/area. His boat wouldn't work for me and mine wouldn't work for him.
Tell us more about the area, number of people and so forth and we might be able to get you better advice.
Here is a neat video of some surface drives in mud.