I allow classes and subclasses from the 2024 Player's Handbook, with a few tweaks and some variant subclasses offered in the below linked documents. I don't allow classes or subclasses from 2014 material but I am willing to port subclasses on a case by case basis.
I don't allow multiclassing. Players should choose a single class and subclass option that suits their concept. If none suffice, I am willing to collaborate on a new subclass that provides some flavor and crossover features that allow a hybrid character concept (within the bounds of balance and fairness).