Can’t speak Monks as I’m only familiar with their healing spec and I don’t think it’s had many changes.
As far as sub goes, it feels like the spec it’s supposed to be. It’s bursty, in and out quick, reminds me a bit of TBC rogue , maybe even a bit more fast paced. I have to be honest though, I only played sub rogue for a couple of hours each recent xpac and switched right back to assassin because it was just hands down better, so all I can say is “sub feels better to play”.
The only real comment I can give is on Priest which has had spells return as well as allowing for spells across multiple specs, which they got rid of in BFA. Hybrid specs feel like true hybrids again because we have access to spells across multiple specs again. This is also very true for Druid , although they are a bit squishy rn in pvp.
I haven’t gotten to play MM Hunter, but I am a hunter fan and have watched several videos on their overhaul. MM is the best it’s been in years, looks fun to play, nice lovely burst. Just look at the leaderboards to see most hunters agree.