Best Flag: Rose, because its flag follows the basic principles of vexillology. It's simple enough that I can envision the flag in my mind when the name Rose is mentioned, which is helped by the fact that it contains no lettering or complicated symbols. The highly visible center symbol of the flag clearly represents the name, and the entirety of the flag only uses two colors. In essence, it cleanly marks off every qualification on the checklist of a good flag. Pantheon, Cerberus, and Acadia's flags also deserve mentions, but Pantheon and Cerberus' are unoriginal owing to the former being based off the Macedonian star and the latter on the Mass Effect organization of the same name, and Acadia's seal is just detailed enough to become indistinct at a small size (e.g. on the treaty web). I'd nominate NPO, although while the flag represents Pacifica very well the triangles and star have no clear symbolism—as far as I know, correct me if I'm wrong—as opposed to Rose's rose literally representing a rose, Panth's sun representing their Greek theme, etc.
Best OOC Poster: @Zeebrus is unarguably one of the most beloved posters on the OWF since she churns out impressive stories with both quality and quantity. I don't know anyone who dislikes Zeebrus, and she has the rare ability to make people laugh without insulting others. In a game where most posts are divisive and controversial, Zeeb stands out like the sun. I'd nominate her for a ton of other stuff, but I think she's been nominated for everything already.
Most Active Player: @CuppyCakeYums has no rival for this category, in my opinion. He's on every alliance Discord at every hour of the day, always either actively chatting or lurking with a comment ready. Honorable mention to @Smith, who also consistently seems to be everywhere. To be fair, though, I'm probably biased by the servers that I myself visit a lot, plus the fact that I'm not taking in-game activity into consideration at all.
Best New Addition to the Community: @Ripper has carved out quite the niche for himself. I know he's already gotten a billion nominations for this category, but his comics are actually something else. Although new, he's made a name as Aargh's leader and as a free-raiding pirate has demonstrated a thorough knowledge of the game's mechanics. Not to mention, his newspaper has a not-insignificant number of readers.
I don't think I've been around long enough to give accurate nominations in most of the other categories, and I'm sorry if I didn't name some people who deserve nominations; these are simply the ones that immediately sprang to mind. Although tbh let's be real, I'm just here to rave about Rose's pretty flag.