Everyone will have their favourites and mine would be Amelanchier canadensis (Snowy Mespilus). Would do best in a neutral to acid soil. Wonderful mass of white flowers on bare branches in the spring, followed by bronze leaves turning to green and small, black berries which the birds will go crazy for (non-poisonous). The leaves will turn orange and red colour in the autumn. Many other varieties, some with slightly pink flowers.

My favorite is the Cornus Florida 'Cherokee Chief'. Grows to about 20 feet, may get a little larger under ideal conditions; large pink & white flowers on bare wood in the spring. Leaves emerge burgundy, then turn green; red & purple leaves in the fall; ruby red winter berries.

I agree with Jimmytheone.

One of the smaller compact crabapple trees might suit you. Lovely pink or white flowers in spring and crabapples for the birds or for jelly in the autumn.

I would also suggest crabapple - really easy to manage and lovely contribution to any garden