The performance of Lu3Al5O12:Ce (LuAG:Ce) and Y3Al5O12:Ce (YAG:Ce) scintillators were compared under γ-ray excitation using photomultiplier tube (PMT) readout. Light yield non-proportionality and energy resolution were measured with a Photonis XP5500B PMT. The energy resolution, obtained in this work for 662 keV γ-rays, was 6.7 and 7.0%, respectively, for LuAG:Ce and YAG:Ce detectors. A fast component in the scintillation decay of LuAG:Ce crystal is faster than that of YAG:Ce crystal, whereas the relative intensity of a fast component for YAG:Ce crystal is higher than that of LuAG:Ce crystal. The coincidence time resolution, obtained in this work for 511 keV annihilation quanta, was 583 and 660 ps, respectively, for LuAG:Ce- and YAG:Ce-based detectors in coincidence experiment together with a BaF2 scintillation detector. Normalized coincidence time resolution was also discussed in terms of a number of photoelectrons and decay time of the light pulse.