Before COVID closed down travel I was lucky enough to travel from London to Saigon by train through Russia etc. I've been writing a series of articles on the trip. If anyone is interested here is a link to the article. I'd vote the Reunification Express, particularly the section from Hue to Danang, as one of the most scenic train trips in Asia!
Join us on the Reunification Express - a train that unites a nation as it winds spectacularly from Hanoi to Ho Chi Minh City, running the full length of Vietnam