Answer is: glycerol because it is more viscous and has a larger molar mass.
Viscosity depends on intermolecular interactions.
The predominant intermolecular force in water and glycerol is hydrogen bonding.
Hydrogen bond is an electrostatic attraction between two polar groups in which one group has hydrogen atom (H) and another group has highly electronegative atom such as nitrogen (like in this molecule), oxygen (O) or fluorine (F).
