VLC has atrocious UI, but don't complain, everybody loves the story of the app so it must be perfect in every way!
It has a ton of cryptic options, but at least it lets you mess around with them and maybe get something usable, where other apps would just give up and shake their head.
I moved to IINA to finally get back to a video Swiss Army knife that just plays video and doesn’t force me into an experience I don’t want… after tweaking a bunch of settings.
A miss Perian, the codec pack for QuickTime, which gave QuickTime and QuickLook that play-anything experience. It played the video and got out of my way.