I got Ace and Whitebeard's death spoiled for me. I was streaming the anime on Funimation's site, and they always show the most recent episodes. So having an episode titled "Fire-Fist Ace Dies on the Battlefield" kinda ruined it for me. It was still pretty emotional when it hit. I also saw one of the later openings (probably Share the World) so I knew Franky and Brook joined and that the crew got a new ship.
Honestly, I got spoiled left and right back when I was playing catch-up. Always saw stuff online about Water 7 and Marineford. Glad I caught up right after the timeskip though.