A completely biased opinion but I think you agree with me that there is nothing like Legend out there in the market. That was the main reason why I decided to team up with Jay and realize Legend's potential.
Now that is out of the way, I'd love to hear about the tools you have tried or explored. Here are some conversational snippets form the old forum.
Thread Where is Legend? - Tana, Wokflowy, Dynalist
think Legend offers more features than similar software, but I am playing around with Tana currently as it’s developing more quickly and has a much more active online community. Still loyal to Legend but it’s not unconditional loyalty. --wecansee
Does Tana have the equivalent of Legend’s ‘Panes’? Without being able to drag & drop between multiple outlines on screen at once, manipulation of large lists is painfully difficult as I found with workflowy, dynalist and every other outliner. --sam
I stumbled upon Legend (Moo.do) about 5 years ago and was hugely impressed: the core structure of the app is so much more powerfull than competitors like Workflowy, Dynalist, etc. The Boards and Panes are really unique. --
Best Outliner blog post https://bloggingx.com/best-outliner-apps.