Anime
It’s best and most convenient to watch all the One Piece movies in order because that’s how most movie series is watched. By watching the One Piece anime movies in order, the viewers can easily comprehend the flow and the plot of the movies.
The One Piece anime movies have their way of presenting characters and concepts hence it’s only acceptable to watch the anime movies in their order of release.
Besides their order of release, One Piece anime movies aren’t connected to the main plot except for the One Piece Film: Strong World because the antagonist from this film made an appearance in the manga.
Hence, it’s highly likely that we can expect some characters from the movies to feature in the anime series. Therefore, it’s always best to watch all the One Piece movies in order.