Trello vs. Todoist
Generally I think with those two tools you will more or less achieve the same. But in my case I use Trello as an overall board for my whole live as a freelancer (contracts, ideas, collaboration and so on). And it is the overall container for the project. So if you had some nice idea for an ui pattern in a former project, you can easily use this in a future project by duplicating the card with ui pattern content (wireframes and all that stuff).
Todoist on the other hand is more project specific. So all the nitty gritty stuff could be tasked via Todoist. For example: Project Phase 1 — Wireframing the navigation. But you will never think about the projects briefing for example. Because this briefing you’ll find in Trello.
Use Trello for all you organizational stuff and Todoist for more project specific tasks. :-)