I think Amethyst and YakiHonne serve somewhat different purposes. Aside from both being full-featured clients, YakiHonne provides superior long-form note functionality, and is setup almost like a digital magazine. It's UX is beautiful, and I think it appeals more to the iPhone aesthetic.

Amethyst, on the other hand, is a more straightforward feed client that provides a more fixed experience. I use Amethyst for most of my Nostring, but use YakiHonne for long-form notes and articles, and when I want to discover and browse the Nostr universe.

I believe there's room for both in the Nostr ecosystem, and don't view them as competitors, but compliments.