I've been using Notion (https://www.notion.so) for a while and have nothing but good things to say.

- It's incredibly flexible. You can model Trello Task Boards in the same interface as writing or making reference notes. - They've got a great desktop client and everything syncs offline. - Latex Support - Programmable Templates - Plus there seems to be pretty neat people behind it

I switched to it 8 months ago or so and haven't really looked back.