Your Favourite Optional Rules and Rules Alternatives
The AD&D 2 has tons of official but optional (e. g. proficiencies) or alternative variants of the same rules (e. g. initiative), especially if you use Player's Options. That is good for the adaptation for the individual needs, but I feel a bit overwhelmed with the choices sometimes, so I would want to study the experiences of other DMs. Which optional rules and alternative variants of rules (including PO if you use them) do you use and why?