Should we buy Paperboy or Sonic&Knuckles (both for Genesis) from the corner game shop?

SonKnuck is an amazing game and an essential for any Genesis collector. But I've played it to death and its common.

Paperboy is an arcade classic that I didn't even know was on the Genesis, is an inspiration for one of the games we're making, and I love bicycles. But it's really a hard and repetitive game because its an arcade port.