[paulmatthijs]

The trick of "proper" GTD is not what to use, but what not: focus on eliminating inboxes. You've got too many.

Triage everything that comes into your (e)mailbox, Slack, whatever. It's the deciding what's actionable and what's not that makes your GTD work. Get the info you need from those inboxes into a single filing system, and stick to it.

Mine is OmniFocus, your mileage most likely will vary.