Hello, I'm going to tell you my experience with LG so you can decide on what you really want, I have not bought either the g6 or the g5, I had a g3 for the past 2,5 years and it broke down recently, what I can tell you about OS support is that LG does not give updates every year or so, when I bought it (1st Frebruary 2015) I received 5.0, 6.0 was annouced but I never saw it comming to the g3 I eventualy got 6.0 after the 2 year warranty, all I know is that half a year later it broke down and I don't know why, (I just came here to talk about the support of the phone) btw don't expect to get updates like on apple.
PS: I might get an S8 or P10 plus.