Wow,
Not enough time left in my life.
I would like to do them all.

I've been researching the TMB. One problem is that dispersed camping is not allowed in most of the Alps. There are huts available all along the trail, but they are reserved nine months in advance. So you have to plan your route in September for your trip the following Summer, which is kind of crappy.

That's the problem with a lot of "bucket list" hikes on these kinds of lists. They are really crowded when there are nearby options that are probably as good or better.

In the Alps, the Walkers Haute Route (Chamonix to Zermatt) would be comparable to the TMB (they overlap at the Chamonix end).
But given the high cost of everything in Switzerland, I might go for the Alta Via 1 in the Dolomites of the northern Italian Alps (near Cortina where the next winter olympics will be held). These are also hut to hut hiking, but at least in Italy, the huts are required to accommodate everyone, even if you don't have to have advance reservations (although you may end up sleeping on the floor).

In Nepal, the EBC Trek is on out and back trek that kills a lot of people with altitude sickness if you are not careful. Most all will use the same crowded trails and huts. The great thing about trekking in the Khumbu (Everest region), is you can go almost anywhere and there will be a lodge with bed and food. As long as you avoid the most crowded trails and months, no reservations are necessary. Even if one lodge is full with a giant group, there will be one nearby that is available. The less crowded trails are probably more scenic too.

But the top of my international trekking list is northern Sweden. The Kungsleden is a long distance trail through the mountains. Most of it is serviced by off-the-grid huts, but still have resupply shops, beds, kitchen, and saunas. Also, in all of Scandinavia, you can camp and hike on almost any undeveloped, unoccupied land with no permits, fees, or permission needed.

Or in another way of thinking you could say the best hike in the world is the one you are on at the time.