The verdict
There is no single winner here because there is no single problem. If your day gets eaten by the inbox, Inbox When Ready is the more decisive buy: about 4 USD a month to put a wall between you and your incoming mail, and a genuinely free Pro licence if you earn under 3000 USD a month. If your bottleneck is everything that arrives as audio, meetings, client calls, your own voice memos, MacWhisper is the stronger tool, and its one-time lifetime licence (around 69 USD on Gumroad) means you pay once and own it. Pick by your actual bottleneck. If you cannot name one, it is almost certainly the inbox, so start there.