While I also think email apps are not great, especially when trying to find a unified experience with macOS and iOS, I think CloudMagic for iOS is pretty good and Nylas N1 for macOS is also very good. maybe if N1 comes to iOS..
I actually sort of prefer email apps with this sort of pricing model; it makes me think they're trying to be financially sustainable rather than just getting acquihired in a year or two. I would definitely pay $7/mo for the right email app. (But I don't know if N1 is it; I added N1 and some other Mac-only email apps to the original article.)