Is monero fungible when you don't even know for certain how many coins are being produced due to an opaque block chain?

No Dash is very different from all of those projects.  Lightning Network is a separate network that you have to lock your coins to for up to a year to make it worth while.  Only those who buy into your chain can be traded with.  it's clunky and ineloquent.  Dash has everything as part of the core network, instant, fungible/private.  It puts the user experience first, not a bunch of complex add on networks that lock you in a corner and nobody will use.  The lightning network might as well be a way to color your coins and make them less valuable due to inability to pull out and convert to something else.

Lord have mercy, "isn't Dash just BTC + Lightning + "some mixing tool"?  Obviously you have no idea what Dash has done.  It's too much to explain here, but I highly suggest you play in Testnet to see how it works, and then if you are interested, read the papers on Evolution to see where Dash is going.  Where Dash is going would be impossible for any single tier network to achieve.