I've really been enjoying Astro recently (https://www.astro.ai/). I was a big Newton/Cloudmagic fan before they shut down in the last month, but nearly everything I liked from Newton is also present in Astro. Unified inbox, snooze/send later, excellent keyboard support, etc.
Also has the best "less important emails" inbox implementation that I've used so far. The whole gimmick of an AI bot I could chat with is just that, a gimmick, but bot the desktop and mobile apps are solid.
Wishlist items remaining: Newton had you have a Newton account that would automatically set up all your accounts when you installed it on a new device, but Astro doesn't do that. Also, I'd love it to automatically pick the right account to send from once I type in the recipient's address, based on past correspondence, like Newton did. But neither of these are even small issues.