I buy slightly older phone in Lots. I clean them, test them and then I change them over to a ROM that runs nicely. Then I sell them at a modest markup. I’ve sold about like twenty so far in the past year and I have about forty waiting to be finished. Due to chronic illnesses I have, I often have weeks during which I can’t make any progress.
I know there are plenty of enthusiasts who would like to run a smoother OS that doesn’t spy on them or waste sys resources on bloatware, but oftentimes those people are afraid to do their own hack for concern they’ll mess up. That’s basically my customer base and I’ve been very happy to help get these devices to folks who want this experience.
I like crDroid, ResurrectionRemix, BlissOS, Lineage, Havoc, /e/, Iodé, and like a dozen others such as generic AOSP based etc. There are like a hundred. I just discovered SuperiorOS I put onto a Moto X4. Superior is quite an apropos name, it’s really sweet!
Samsung and Motorola are a smooth process (provided not restricted due to carrier or because it’s a prepay). Some LG are very good as well, but too many are not accommodating and also lots of them crap out. I do like my G4. I have about thirty devices I use somewhat regularly for this or that.
There are plenty brands, though, that I’ve not yet tried out.