What old USDA zone are you? They redid the USDA zones a year or two ago. IF you're old one 3, go for old zone 3 trees. The list gets alot smaller.
Starting to like 30-06 more and more. They grow like weeds. Violi's from saint lawrence nursery is another good cold area slow n even into winter dropper. I've had 30-06 on anty survive -35 deg F. They also have sweet dog, winter wildlife, all winter hangover, and MN 1734, and have kerr. They use antonovka rootstock, some get siberian crab much like dolgo.
Take a look at sandbur's crabapple timeline thread. He is up in the northern part of the US like. Thought Minnesota, could be WI though. Midwest deer apples and bluehill sell crabs he has found over the years. Got big dog, buckman, and courthouse.
Get double or triples of some trees. Trees take alot of work, I'd get a few more, but thats it.
I got 40 or so at home and they seem like alot of work sometimes. At a camp I lease with a few guys I have 4 spots with 7 or 8 trees a piece and 4 good eating ones right at camp. IF your not ok with going back where you hunt and distrubing wildlife, its best to plant a few close to the camp you can harvest and enjoy yourself. Most spots are 1/4 to 1/2 acre foodplots with the apple trees to the north of the plot. Keep in mind you need to not rototill or dsic within 20-25ft of an apple tree. I do mostly notill up there. and some trees are set back more from the plot due to rock piles, steep edges, etc...
My camp is zone 3. I try to plant them on siberian, dolgo, or antonovka rootstocks. Most were grafted by me. At home i like m111. I do have a few M7's. I got them because I wanted a specific variety and they only had M7 left. redfree, sundance, and a M7 on enterprise for a friend who bought a new house.
A mix is good, a few quick to make apples like m7, m107,109,or 111. And a few monsters on dolgo or anty. I got some M111's in a single row 16ft apart. But 20ft is ideal. Got the majority of them in a double row 25x25 apart. Plenty of room for m111's. I do have a few B118s and an anty or two t home too.
Good to plant a few different rootstocks, maybe one type likes your soil more than others.