I think one of the most valid critics against bitcoin is about its privacy and it's one that Monero people always cite. One argument that I think is good is that dark markets are always transacted with XMR, showing that it's the only private solution out there. I guess BTC has coinjoins and other tools, but they comes at a cost and do not always assure full privacy. There's also lightning, but the receiving node privacy is not that good either.
I don't know much about ecash or dark markets, but the way I see it ecash is very hard to track once it leaves the mint, right? Would that be a solution for fully private transactions? Is it actually being used now on those markets?
Maybe @calle can enlighten us on this.