I've been rocking NVAlt (with SimpleNote on my iPhone) for a while now. It's just a basic note application but I use it for scratch space, quick notes, gift ideas for friends/family, etc. It's my person central knowledge base (even though it's not organized great, it's more of a knowledge dump). I'm not particularly attached to it to be honest but any replacement would have to meet the follow criteria:

* Light - I don't want "yet another electron app"

* Hotkey-able - I need to be able to assign a hotkey to quickly show/hide the UI. This ONE feature is huge for me and changed how I used NVAlt once I mapped Ctrl+1 to show/hide it

* Mobile clients - iOS needed, android would be nice

* Sync service that I can trust OR using iCloud/Dropbox as a backend

I'm half-considering attempting my own notes app (for the desktop and maybe iPhone) once Swift UI ships since NVAlt doesn't do a ton so I can't imagine it would be terrible to re-implement. I would like to add some minor features to it (Maybe basic to-do list or scheduled reminders) and fix the damn smart quotes thing (I have been bitten too many times from making small tweaks to code/json I throw into it for just 1 second and the quotes being those stupid smart quotes).