Looking at figure 4.2 here, we can see experimentaly that cyclohexane is more polarizable than benzene.
Why is this the case?
Intuitively, I would think that because the orbitals in benzene are more delocalized, the electrons in benzene could move farther in reaction to an applied electric field, thus creating a larger dipole and being more polarized than what is possible in the localized orbitals of cyclohexane.
The only counter argument I can think of is that the carbons in benzene are SP2, and thus more electronegative than the SP3 carbons in cyclohexane so that even though the electrons have more space to react to an applied field in benzene, they are held tighter to the nuclei and therefore form less of a dipole. However, something about this argument doesn’t seem convincing to me.