This is a very difficult question to answer because arguably, no such volume exists yet. The historiography of the Vietnam War is highly contentious and politicized, but there has been some very good strides in recent years towards new and more comprehensive scholarship. In that regard, if we are talking about a volume that attempts to strike up that sensitive balance, I recommend Mark Atwood Lawrence's The Vietnam War: A Concise International History. It is a little bit on the older side (first published in 2008), but it was written during a time in which innovative research was being made on the war that expanded our understanding of the war beyond an overly America-centric view. Lawrence draws on academic scholarship, keeps quite the balanced tone, and the concise nature of the volume means that you receive a neat and good overview that does not feel too heavy and leaves plenty of space for in-depth reading on parts that you find interesting (or that you feel might be missing!).