I've had very good luck with Okame. It's been amazingly pest and disease free for many years even though native and other cherries nearby show signs of the usual prunus problems. Unfailing bloom as well, no matter how harsh the winter. The little pink parasol blossoms are very nice if not as large or screamingly pink as some other cherry varieties.

Unless in a very favorable coastal location, cornus florida is not, in my experience, well adapted to New England. The various cornus diseases, especially anthracnose, attack the trees when they are stressed. Colder winters and less summer heat than they experience in their native range can quickly lead to infection.

Not at all tooo late to plant.

I'll go with Cherry. They bloom best under the sun than in shady spots. Both trees are susceptible to some diseases and pests but in general, Dogwood tends to have fewer.