I always come up against the same problem: does one change one’s home currency to Euros, then change Euros to CUC?  It seems like it’s still better to do that then just go in with US Dollars, no?
Please advise!

US dollars are penalized 10%, so you dont want to exchange them in Cuba.  Whether you buy Euros or British Pounds or Canadian Dollars (just to name some), gets you the “real”  echange rate, so any of those would be preferable.

Manfredz is correct. And even w/o the 10% tax on US dollars , it would still be a good idea to use Euros as that currency is still near an all time high vs US dollar