How do you say I love you Paris in French?

J'aime Paris. "Aimer" is to like/to love in French. You simply have to conjugate aimer in order to say you love something.

I love - J'aime

You love (informal) - Tu aimes

Il/She loves - Il/Elle aime

We love - Nous aimons

You love (formal) - Vous aimez

They love - Ils aiment