The quickest of looks by me indicates US 19 from I-77 at Prosperity, WV to I-79 northeast of Charleston is 4-lane limited access and looks to be of fairly recent construction. It would thus appear to be a good route to run from I-77 starting in western NC to reach I-79 and pass by Pittsburgh to Erie and on to Buffalo NY.
Any recent experiences on US 19 east of Charleston, WV?
Other routes from Raleigh, NC to Buffalo appear involve I-95 and a load of two-lane roads through north-central PA. Mapquest shows I-99 and US 219 from the PA Turnpike all the way to Buffalo being around 60 miles shorter, but with a plethora of small towns and much in the way of 2-lane roads. Besides that, reaching the PA Turnpike at Breezewood via Falmouth and Winchester, VA, is a fairly lousy run from Raleigh to begin with, in my humble opinion.