Wikipedia

A Singaporean passport is the strongest in the world. It gets you access to 193 countries, so everywhere but NorK or Somalia. Japan, South Korea, and most of the EU are close follow ups, although I don’t know how well Schengen passports would do in either Iran or Afghanistan right now. Probably best not to navigate through Kashmir right now either regardless of where your passport is from.

Interesting question. The two problems with the Hippie Trail today are Iran and Pakistan. So perhaps a Chinese passport. That will get you royal treatment in Pakistan, which is basically a Chinese vassal state. The other problem, Iran, is more complex. The risk there is kidnapping by its rogue government on spying charges, and so the main priority is not to be Western. But I'm guessing that these days nobody in that region, including the Iranians, wants to be on the wrong side of the Chinese.

BTW, as the article says, people do still complete the Hippie Trail. Apart from borders, the main obstacle is Baluchistan, a 600km stretch of desert in western Pakistan. It's the only way to get to India without going thru Afghanistan, but unfortunately it's just as infested with jihadists and other insurgents. So the train line is off-limits and the handful of tourists have to travel with police escort the whole distance, sleeping in the fortified police stations. An ordeal that takes a week or so.

I know this because I looked into doing it a couple of years back.

That sounds like a it merits a complicated threat matrix of who hates who, lol

I'm not sure there is one. Maybe China?