www.makemkv.com

I have been using MakeMKV for a few years, before I used DVDfab a lot but now I only use passkey now and again, when I found MakeMKV I found it to work better and as I use it a lot I bought a copy instead of the free key.
I have a lot of DVD's Blu-rays and 4K Blu-rays, at first I would rip everything to MKV files and also all the extras, This was a pain to do renaming all the extras but it's what I did, after some time I found problems with Blu-rays, forced subtitles didn't always work when someone spoke alien or French etc, I then found if I ripped a film in to the folder structure forced subs would work, but then I hit another issue, with the folder structure containing a lot of files if a file got corrupted the whole film and extras wouldn't play, so now I rip to folder structure then use Imgburn to make an ISO, all good now but Kodi on an android box doesn't like ISOs, so I ended up getting a Zidoo x9 box, again all good but even the Zidoo box fails on some rips.
Long winded I know.
My question to you is what do you rip to?
What player do you use? and I know Plex doesn't like ISOs
I hope to soon find the right hardware to build my own player maybe based on libreELEC if it can do 4K HDR ISO with menus etc

I use .mkv files with Plex. I find that forced subtitles work well if I find the subtitle track that is the forced subtitles and set forced and default flags to true in the .mkv file.