Monarchy or dictatorship — if you got a “good guy” or “the guy with whom I agree” - then a lot of stuff gets done.
But I think the only modern example of this was Lee Kwan Hua from Singapore. He modernized singapore rapidly, but imprisoned folks who opposed him - so if you were one of those then he was bad.
I think the Republican form of democracy is the least bad form of government for now. Monarchy is just “do i want to be ruled forever by this idiot?”