Which has greater inertia a large mass or a small mass?

A large mass.

The traditional view is to refer to inertia in terms of Newton's First Law of Motion.

However, it became common for Physicists to use the mathematically more useful Newton's 2nd Law of Motion to describe inertia in terms of how difficult it is to change the momentum of a body. The 2nd Law of Motion tells us that Force = Mass x Acceleration. "Inertia" in this context is thus directly proportional to the body's mass.