I thought it would be a good idea to talk about which phones are good buys based on which can be de-googled (or rooted at the very least) if the user chooses to. In my experience I've just about ALWAYS owned Nexus devices, or phones that are really well supported on xda. (Galaxy Nexus, Nexus 4, OnePlus one, Nexus 6, Nexus 5x, and now the LG G6 - waiting for roms)
Here's the supported device list from lineage OS: https://wiki.lineageos.org/devices
Keep in mind these are officially supported, and not counting a bunch that are unofficially supported and will probably be official later on. For example I have the LG G6 US997 version which I'm fairly certain will eventually be officially supported. If you check the original development page for your specific device, you can get an idea of how much it's being supported as far as roms and twrp goes.
Another phone you might want to consider if you're on a budget is the Blu R1 HD with Amazon ads for $60. As soon as you get it don't update it, root, install twrp and install a non-Amazon rom with root. Lineage is out for it as well, but I don't think the camera is working yet (haven't checked in a while).
If I were buying a phone right now these would be what I recommend at each price point:
- $60 - BLU R1 HD
- $100 Moto E or G4 (check support on xda)
- $200 Moto g5 plus
- $300 zte axon7 or honor 8
- $400-450 LG G6 (US997 or H870) best smartphone for the money I'm pretty impressed by it.
- $500 Samsung S8 if you can find it for this cheap and you like the edgeless screen.
Xiaomi makes some great cheap phones, but doesn't support many US bands.
I don't recommend the OnePlus 5, but if you can find the 3T for a good price that's pretty sweet.
Lemme know what you think and if I missed something.