I rank Spain crimes a bit lower because South America colonization is far in the past, in an era where certain crimes was not considered much crimes from the point of view of most populations, otherwise they would be at the top position, perhaps counting also they religious crimes against also their own citizens.
Anyway any power have a blood trail, that's just a rank for the most "recent" ones...
But, no, Vietnamese people can not get French citizenship on special conditions and never could. But they was killed & tortured on the grounds of owning too thick and too long stick, and French soldiers sent postcards with such photos to home! It was not 18 or 19 century, as in Americas, but 1910-1920!
On the other hand, British not only build roads and railroads in India (Myanmar railroads built by British colonial administration are still in use, including some gorgeous and highest mountain bridges), but cut weavers' hands in India, too.
Ok, I can not rate them all. It is just bad.
Belgians in Africa are unsurpassed, though :-(