Cruz
A couple of counties near the border of Canada (EX: Hamilton County) that tend to be more conservative.
I hope that this is a joke. (Although Hamilton County is weird; then again, it contains barely 5,000 residents and is the only county located entirely within the Adirondack Park.)
Cruz's best part of the state should be rural western NY, i.e. places like Wyoming and Allegheny counties. Expect Kasich to run well in the most affluent Rochester and Buffalo suburbs, the Albany area, and the Mid-Hudson. He may also do well in the ancestrally very heavily Republican parts of Northern New York, esp. near Vermont.
My early prediction for Trump is that he'll run very strong in the less affluent portions of the Buffalo and Rochester metro areas. His best county in upstate NY might be Jefferson (home of Fort Drum and one of the highest concentration of veterans in the Northeast).