This is more so a DPS prospective.
All classes are viable at the hardest content & there is no worst class. It's all dependent on the player skill & experience in my judgment. Every class has their little niche they're good at, etc.
Been playing Darktide for nearly 4-years now since beta & have over 4.8k hours dedicated to the game thus far. In Vermintide 2, I have about 6.2k hours. Every patch update, I modify what the current Meta builds are for each class. I also do support builds as well. Welcome to my journey, fellow travelers!🙂Enjoy!