Here's my 2cents and comparison
Both of these cranksets are in the running for "best value" cranksets. Neither are too expensive for what you get.
Here is my comparison:
Bottom Bracket: TIE - Suginos use any Shimano tapered 109BB and Miche's use any standard 102Campy BB (as well as the 107Miche BB). But the Miches work much better with the Campy option
BCD - Sugino wins here with the 144BCD. But how often do you change your big ring? You already have extra Miche rings you say, so this really shouldn't be an issue. Sure more options for Sugino, but its not like its hard to find Miche compatible rings (Miche and TA both make them)
Stiffness TIE - I've ridden both Miche and Sugino 75's and I've found very little flex in either.
Look (sexiness) Miche wins. They are so much nicer looking in my opinion. But the Sugino's have a nice old school look to them
Price Tie. Both of these retail on average around $165-$170USD. You can obviously find deals for either.
So my suggestion would be to keep whichever compliments the rest of your bike setup.