Why is it 'sad'?
The dead remains dead and all we can do is remember them. However, the living have dual responsibilities: They are stewards of the present and must prepare the present for the future generation.
In terms of history, if we are to look at the scale of 'goods' vs 'benefits', then China is the worse. For France and the US, France was colonial master of Indochina for about 100 yrs, and the US military involvement in Viet Nam was about 25 yrs. Combined, theirs was a mere blip when compared against China's one thousand yrs of repeated invasion and subjugation of Viet Nam.
So if you do not like to look at it in terms of history, then looking at Viet Nam in the present still not make China the better choice. Remember, China just claimed the entirety of the South China Sea as territorial waters, effectively imprison most of Southeast Asia. So how is that better for Viet Nam, Laos, Cambodia, and Thailand?