All 20 survivors. The criteria: how well they survive and keep up late in Monsoon and long runs, and how forgiving they are. Our opinion; difficulty is listed separately.
Strong late into Monsoon and long runs, and forgiving.
Very good, with a weak spot (health, mobility or item dependence).
Can win, but struggles more than the rest in long runs.
Not rated yet: they come from the newest expansions and we have not played them enough.
For us, the S tier: Engineer, Railgunner, Acrid and Loader. They stay strong late into Monsoon and are forgiving.
Commando, Huntress, Engineer, MUL-T and Captain: all marked as easy.