I have not researched Blu-rays enough before buying my first one. You can't even play one on Windows by default, and VLC and MPC both require following arcane instructions from user forums to make it work. That's the last time I bother. DVDs were the superior format.
@Gargron I appreciate that Blu-rays can't be taken away from me, and their DRM is pretty suitably broken generally. so it preserves ownership at reasonable quality. But yeah playing on a PC is incredibly annoying, paid software is the most reliable way to do it, and 4K Blu-rays are no longer supported at all because the DRM relied on a deprecated processor feature.