When it comes to an anime that is romantic, it's kind of hard to choose just one but if I had to choose three in total then I would have to choose these three:
Ugly yet beautiful world
Ef a tale of memories
Waiting in the summer
Well what about you, what is your favorite romantic anime?
yahari ore no seishun love come wa machigatteiru
Probably Lovely Complex.
Say I love you or kotoura-san
My best three:
Kimi ni todoke
Ore no Monogatari
and............ Diabolik lovers.....
....Jajajajaja, okey no, its Wotaku ni Koi wa Muzukashī XD