Personally, I'll always feel exceptionally proud of working on Panama Papers. My work was in no way particularly important to the project (just implementing some frontend), but it set such a high bar on meaningfulness so early in the career that it's going to be very difficult to top it.

Over all, I feel like EDRi (https://edri.org/) is doing exceptional work over here in Europe. Think of EFF, but instead of being one organisation on a federal level, it's made of a bunch of smaller organisations that work in different nations on intertwining issues, be it net neutrality, reverse engineering Big Tech's algorithms, or helping the citizens exercise their GDPR rights. It's a small front against the Big Tech, and they need as much help as they can get in order to put up a fight.