I will take your word for it, I know about LG, I once had the G3, had nothing but problems
Do any of these brands work on sprint and where can you purchase them...I current have a Nexus 6p and would like to keep buying pure Android phones
After doing some research unfortunately vernee does not support usa 3g and lte bands so thats a no go. The only other near stock android phone on the list, the oneplus 3, does support the us bands and should work on sprint easily. The other options are not stock androids. If you do Decide to go the non stock android route then lg g5,le eco pro 3, le max 2 , lenovo zuk z2 and z2 pro and Asus zenfone 3 works fine on sprint and all networks in the US.
Just bear in mind the leeco phones have no audio jack like the iphone 7 but do come with usb c to audio jack adapter and compatible earphones are available ,so if that's a dealbreaker for you then .....
The best place to buy the xiaomi,zuk, asus,oneplus 3 and le eco are gearbest.com, banggood.com,geekbuying.com or honorbuy.com. but gearbest are by far the most legit 3rd party retailer on that list.