I have a thing for crabapples, especially white flowering ones. My favorite is this beauty, a good disease-resistant cultivar sold as Sugar Tyme (Malus 'Sutyzam'), which is in bloom right now.
What makes it great is masses of gorgeous, fragrant flowers in May, followed by long-lasting red fruit, which persist almost into winter until flocks of migrating cedar waxwings swoop in to clean the berries off.
I'm a fan too of 'White Angel' and 'Donald Wyman', also white-flowering crabs. Aside from the white ones (I have a spot between our old silo and the farm pond that I call the crabapple orchard), I planted a number of purple-leafed, pink-flowering 'Thunderchild'. Unfortunately, they've been duds, producing fewer flowers than the white cultivars and losing their leaves half way through the summer. I've had them for three years now.
My husband is quite ruthless about turfing under-performing plants - maybe rock gardeners are less tolerant - but I like to give them a sporting chance, especially trees. But if the Thunderchilds don't improve this year, I'll bite the bullet and pull them out. There's always another tree to try out...