Like the other anon said just forget One Piece, you can watch a hundred better series within the same time-frame that you need to catch up with that. I'd recommend these series, there're many different styles and stories, some of theme are used a lot in memes too so they're must-watch, besides those there're some of my personal favorites:
Clannad/Clannad: After Story
Code Geass
Ef A Tale of Memories
Fate/kaleid liner PrismaIllya
Gosick
Inu x Boku SS
Isshuukan Friends
Kiniro Mosaic
KonoSuba
Log Horizon
Mahou Shoujo MadokaMagica
Maoyuu Maou Yuusha
Mayoi Neko Overrun!
New Game!
No Game No Life
Papa no Iukoto wo Kikinasai!
Sankarea
Shakugan no Shana (not the dub because it's shit)
Shinryaku! Ika Musume
Steins;Gate
Suisei no Gargantia
Tasogare Otome x Amnesia
Watamote
Yuru Yuri
Zero no Tsukaima
Most of these have movies and extra OVA episodes too, you can use
anilist.co to see all details about any series.
