There is bit big difference in sensor size here, Canon G1X Mark II is a 1.5inch sensor camera on the other hand Ricoh GR features APS-C sensor.
Canon G1 X Mark II features 12.8 Megapixel 1.5″ (18.7 x 14 mm) sensor with a ISO rang up to 100-12800. The Ricoh GR features 16.2 Megapixel APS-C (23.7 x 15.7 mm) sensor with a ISO rang up to 100-25600.
Verdict: We can clearly see that Ricoh is giving us more details compared to Canon G1X Mark II, so we highly recommend you to buy Ricoh if you want better image quality.
Buy Canon G1X Mark II from Amazon || Buy Ricoh GR from Amazon
For specification comparison- Canon PowerShot G1 X Mark II vs. Ricoh GR