I've only heard it said that "democracy is the worst form of Government except for all those other forms that have been tried from time to time", not capitalism and economics: https://winstonchurchill.org/resources/quotes/the-worst-form...
Got any evidence for that?
Forbes, 2019: https://www.forbes.com/sites/yuwahedrickwong/2019/04/19/econ...
NPR, 2009: https://www.npr.org/2009/10/26/114163098/a-spoonful-of-socia...
LSE Economics Society essay question, 2018: https://www.tutor2u.net/economics/blog/lse-economics-society...
I also clicked through ten pages of Google search results for "capitalism is the worst economic system, except for all the others", each of which showed the literal quotes in the preview excerpts, at which point I became too bored to continue.