@killyourfm @Vivaldi re "not sure how I feel about 'database of messages ... is maintained by Vivaldi'" - no privacy issue lurking here, this is strictly within the local client.
TB defaults put accounts and folders in the front row, I have to turn on unified inbox. Yes quick filters exist but TB feels like made for filing. Vivaldi is the other way around: unified inbox and filter toggles first. Plus I like the browser integration.
Unsurprisingly TB is much more mature & feature complete (c:=