I’m not a huge fan of F2P otome, so I’ll suggest checking out Otome Obssessed, which is a good source of info and reviews for F2P mobile otome games.
Idea Factory have a couple of their paid titles up on iOS/Android. Hakuouki was one of the first otome titles released in English, and it’s still a great example of the genre. If you haven’t played it, it’s serious, long, and plot heavy. However, the PS Vita rereleases (Kyoto Winds/Edo Blossoms) are superior because they feature significant extra content including several extra routes for new and existing characters.
Hatoful Boyfriend is an excellent otome game with a really interesting, quirky story, providing you can get over the initial novelty value of dating pigeons. It’s available on mobile, as well as several other platforms.
I second the recommendation above for Collar x Malice, although as noted, it’s PS Vita only unless you want to play in Japanese. Code: Realize is also a good VN on the Vita.
If you’re willing to play on PC, Hustle Cat is a great visual novel that’s really cute and well written. It’s from a western dev, and it’s a bit shorter and more accessible than many of the classic Japanese VNs.