With regard to apples there is a decent selection for most locales. The coldest spots, however will find it necessary to seek out the toughest of the lot. Among them are Dolgo crab, Ranetka crab, Selkirk and Siberian crab. There is evidence that malus prunifolia too is very cold hardy.
Siberian Crabapple, malus baccata, is likely the most cold hardy. It has had some criticism in Alaska as being a bit slow in growth (too much so for some folks) but may be part if the reason for its high survival rate. Slower growing varieties and species by and large have tougher, denser wood. There are reported issues with compatibility in some variety combinations. Some anecdotal evidence states that cultivars with crab in their ancestry are less likely have rejection.
..more to come..