I'd choose Samsung because while they're both no Google, AFAIK Samsung, as bad as they are at it, are still better than LG in terms of updates. I've seen LG flagships that are 8mos behind on security updates. At least the worst for Samsung (barring carrier craziness) is 3-4mos AFAIK, and that only occurs when the time for launching the beta test for the next OS update is coming close.
That and things like SideSync and SmartSwitch makes Samsung my choice. SmartSwitch (paired with Helium and standard cloud) makes moving between Samsung phones easy even when unrooted. SmartSwitch also allows you to create backups of the device onto the SD card. SideSync allows me to control and view my phone contents on a PC or compatible Samsung tablet. This is the closest thing to proper syncing messages across devices for Android that I know of. Plus it helps with broken screens because once you've set it up before breaking the screen (hence set it up as soon as you have the phone running), SideSync can use your computer as display to retrieve your data even if the phone is locked since the phone pushes the display to a window on a PC for you to control with mouse and keyboard. You can use that to create an SD card SmartSwitch backup, and wipe the broken phone before sending it to the repair shop.
However, do realize that the LG has a wide angle camera, if that's important to you. I think the LG camera app also handles colors better (yellows seem washed out on pictures/video Samsung takes). It also has a much better DAC, so if you're an audiophile, it's gonna work better for your wired headphones (won't matter if you're using wireless). Plus it has a flat screen (selling point for a lot of people nowadays). It also has a 2 year warranty compared to Samsung's 1 year.
Basically hardware wise, LG is up there. Samsung just have better software options (for me), and (for what it's worth) slightly better update history.