If I had to pick one bike to take to a third world country, it'd be an early '90s pre suspension high end mountain bike. What's not to like, 36 spoke wheels, enough gears to be useful, not looking valuable enough to steal for mega cash, room for fattish tyres. Usually eyelets for racks and having the geometry to cope with being heavily loaded. Being high end, usually a cassette rear wheel. Oh hang on, when I worked in a third world county, that's what I rode...
Now I tour on a replica, a Surly Troll, same thing, with more eyelets. Unfortunately 26" is being left behind in terms of tyre technology, the range is not expanding like 27.5 and 29 is now. But wheel size aside, if you look at any expedition bike, it's a 90's MTB.
Pretty well the pinnacle of practicality.