I’m not clear on the protocol for mentioning other products here, so please delete this if it’s not appropriate.
If (like me) you’re an old-time Ecco hand, you might want to look at Sheetplanner (www.sheetplanner.com). It’s in beta at present and it’s no alternative to TB in terms of managing and organising notes (not even close). But it does use the Ecco model of an outline with columns and has great flexibility. I’m using it as an adjunct to TB and instead of OmniOutliner/iThoughtsX and I’m enjoying it.