What is "viable" dps and healing class for now?

[Overhealer]

Hello everyone. My friend left for Shadowlands and got his account. Decided to play here on BFA. Checked armory etc and still have no clue - what is a healing/dps viable class here right now?

Im talking about class that fit raids/m+ . I know I can go whatever I want but for example everyone guiding me to Rsham but have not see them a lot in armory. 

Is there any tier list what is good/bad/average right now?

Have a nice day everyone and thanks for every answer.