Sturdy, easily fixed, easily sourced parts. That's what matters for me.
Sure like any cyclist I read and dream about the latest, most advanced and most expensive bikes/groupsets/wheels and what have you. But I'm no road racer. I travel to remote parts of the world, places where you can't find a bike shop for hundreds of kilometers. What I need, is reliability.
On long tours, I run 1x9. I like it because I know I can get more than 15.000km out of my transmission. The chain is thicker which means less likely to break. I really like one by. When you have a big cassette, I feel it's enough for most terrains. You just need to choose your front ring wisely.
On the Silk Road, I will be riding an Omnium CXC. A sturdy steel frame is always a good choice for long tours. It's confortable and if anything happens, it's easier to get it fixed than any other material.