Serscruffington streams fairly consistantly and does both 5 man mythic+ runs as well as 10-box raiding on his own:
https://www.youtube.com/results?sear...erscruffington
https://www.twitch.tv/serscruffington

As far as comps...

If you're just looking for straight up performance, I think BM hunter is still the go-to DPS class since all of their DPS is doable on the move. Ranged in general have an easier time due to more free positioning.

Tanks I feel like give quite a few options and it's more or less down to preference. Most common ones would probably be Blood DK and Prot Paladin, although I don't see why you could not go for a Warrior, Brewmaster Monk or even a Bear Druid if you wanted to.

Healers I can't really comment on that much since I've only tried a few specs this expansion.