Just outside of Ellicottville, there is Little Rock City State park-with a great little network of trails! If you are looking for day trips-Ithaca has a bunch of state parks with great trails (Buttermilk, Treman, Taughannock). Also out towards the Finger Lake area-you can hit up Watkins Glen which is gorgeous.

Closer to Buffalo, there are Spraguebrook & Hunters Creek parks which have some good trails for hiking or MTB!