Keep in mind that I was heavily invested into Naruto when I decided to start watching One Piece. It was at the point where Naruto was nearing its end and I needed another series to follow, and One Piece was right there at the top and didn't look like it was anywhere near ending, so I picked it up.

Honestly I hated it at first. We're talking anime initially. I hated the art style, animation and the complete lack of seriousness. I think I dropped it somewhere around the end of Arlong's arc. Even though I found Nami's story in that arc great, it wasn't enough to grip me and the slow transition over into Alabasta really killed it for me.

Then several months later I stumbled across a YouTube AMV that was based around the crew's separation at Saboady. I was completely surprised by how epic the series looked there and I even shed a tear at the end of it when Luffy started begging Kuma to stop, despite the fact that I didn't recognize characters like Robin and Franky.

Yeah, I spoiled possibly the biggest moment of the series for myself, but it got me to restart the entire thing and I don't believe I would have ever thought about going back to it were it not for that spoiler. Now I'm caught up with the manga and it's possibly my favorite manga of all time.

On a similar note, I find that usually it's the major spoilers that get me to follow a series. The only reason I picked Game of Thrones up was because of the season 5 death and all the buzz surrounding it. (I don't really like the show, but yeah, spoilers aren't always that bad, at least when they're not deliberate with ill intent.)