Mona (the Apple Platforms Mastodon client)

Aside from "this app have a lot of cuties inside it", I think it is feature rich (decent multi-account support, auto-drafts, schedule send, custom fonts, custom post actions and tab bars, etc etc). It also works across major Apple platforms meaning I get the same experience across my devices (the macOS App supports multi-window which fits the "go through timeline -> open a ton of posts as new windows in the background -> then deal with them one by one" workflow of mine)

Runner up is Acorn (macOS image editor), I use it to make memes and profile images -- easier to use than GIMP, pretty similar to photoshop without all of the adobe shit.

// if you ask 2005 kuriko they might have said Hamster Ball Gold and if you ask 2018 kuriko they might have said LaTeX