If you could only choose one type of loading method for pullovers, kettlebells would be the winner.
The kettlebells provide a constant angle of pull because they hang behind and below the arms, which puts constant tension on the targeted muscles. Contrast that with pullover performed with free weights that provide tension predominantly in the fully stretched position with little tension throughout the other portions of the movement.
The decline position produces the largest range of motion of any pullover variation. It also provides more constant tension, similar to how a cable or machine would.