Whenever someone asks me which order to watch 'Attack on Titan', I get excited and tell them the simplest, clearest route: follow release order. It preserves the mystery and emotional beats exactly as the creators intended. So, start with Season 1, then Season 2, then Season 3 (Part 1 and Part 2), and finally the Final Season (which itself is split into Part 1, Part 2, and the Part 3 specials). Watching in release order gives you the slow-burn reveals and soundtrack hits at the right moments.
If you like extras, sprinkle in the OVAs after the seasons they relate to: watch 'Ilse's Notebook' and the other early OVAs after Season 1, and save 'No Regrets' and 'Lost Girls' until after you’ve met the characters they focus on. Skip the recap episodes until the end unless you need a refresher. Personally, I rewatched the whole thing in release order with a friend and the final twists still landed hard—so that’s the way I usually recommend to others.