I’ve been looking for a decent Mac client for Facebook Messages, and I think Astro might be it. There are plenty of features perks here like chat history, stickers, a screen snapping tool, control over notification display and sounds, and more. Plus, you can customize whether messages are sent with Enter or ⌘ + Enter.
Astro also has a bunch of built-in themes for changing your chat layout. Some offer an arguably cleaner design, or shift your messages to the opposite side like Apple’s Messages. One theme, called Star War [sic], makes your conversations look like the opening story text from the films.