Solid sphere reaches the bottom first because for solid cylinder ${{{K^2}} \over {{R^2}}} = {1 \over 2}$, and for hollow cylinder ${{{K^2}} \over {{R^2}}} = 1$

Acceleration down the inclined plane $\propto {1 \over {{{{K^2}} \over {{R^2}}}}}$

Solid cylinder has greater acceleration, so it reaches the bottom first.