Most Motorola phones have good support for custom ROMs, although you should of course check your specific model against lineage's list or XDA before buying it. In particular, Motorola doesn't do anything to prevent you unlocking the bootloader; you just get an unlock request code from fastboot, plug it in to their website to get an unlock code, and then give that back to the phone over fastboot and your bootloader is unlocked. They also have SD cards and 3.5mm audio jacks on most (all?) models, if you care about that. The only downside that I recall off the top of my head is that their NFC support is really spotty; a few models have it, but most don't.