I saw people claim the V20 had bootloop issues as well, can't recall where exactly I saw that, think it was some Android forum. Given their track record (the only real home run device LG has made was the G2 and they frankly seem to be bumbling through trying to figure out how to make phones that don't have some glaring flaw of some sort). The main reason the G series is popular at all is because they pretty much have to sell them for hundreds off pretty shortly after releasing them just to get people to buy in. Otherwise they've basically been ok but generally flawed phones. I'd almost say LG should just target sub $500 on the G series from the outset (something like the Moto X), but they'd probably find a way to screw that up so then it'd be like they should've targeted $200 instead.
The depreciation matters to me as if it's drastic there's a reason for that. And it's more about the value you get from the outset. No way am I going to pay more than $500 for any LG phone anytime soon, and even then it had either be excellent or come with a bunch of other goodies. At this point, people basically should be expecting a bunch of good deals and a very good device from Samsung, so LG had better offer an even better deal or a better device (and it's looking like the G6 is not going to be better than the S8 unless the latter has some major flaw or defect). The current LG deal is good but I don't think it beats the S7 deals from last year and it's not compelling enough otherwise to get me to care. The Chinese companies are offering up comparable (and plenty of times superior) hardware/specs for much less from the outset. I mean the Axon 7 had compelling hardware (has features I'd take over the G6 personally, namely AMOLED, higher quality audio), unfortunately it falls short in the software. But they are improving (if them or Le Eco would just figure out that they could make massive inroads by offering a stock Android)
Not sure why you think those are odd to cross-shop since they'll likely be two of if not the two best Android phones you can get. Yeah, I'd buy something cheap. Actually I'd use that as an opportunity to try a device that there's a decent chance I wouldn't want to keep but try out, and then relegate that to like a backup device or something. Could jump on the G6 since the deals for it are decent, but I'd probably go for something a bit older.