If comparing hardware specs (apples to apples (excuse the pun), ignoring software performance and optimizations), G3 beats the iphone6S.
G3 3GB ram, 4 core cpu, 13MP camera, IR sensor
6S 2GB ram, 2 core cpu, 12MP camera
Here is LG G3 specs:
Large 5.5” Quad HD Display
LTE, Wi-Fi & GPS
13.0 MP Camera with Laser Auto Focus
2.1 MP Front-Facing Camera
32 GB Internal Memory/ 3 GB Ram
Expandable Memory up to 128 GB
Qualcomm MSM8974AC Snapdragon 801