During pure rolling, the work done by the friction is zero. Therefore, we can apply conservation of mechanical energy.
mgh=21mv2+21I(Rv)2
⇒mgh=21(m+R2I)v2
⇒v=1+mR2I2gh
For a solid cylinder mR2I=21 and for a solid sphere, mR2I=52
vSphvCyl=1+211+52=1514