Kyrgyzstan is an ideal place if you are lacking some spontaneous decisions and adventures in your life! There are mountains waiting for you to go for a hike, and yurts to have a nice and exotic stay. You can feel the vibe of Soviet Union in the cities, and you need to keep in mind that everything always works, even if you are sure that nothing works :D
Even though you can find super beautiful nature in Uzbekistan, it's more famous for stunning ancient cities. Feel the vibe of the Silk Road, get lost in the old streets, enjoy the beauty of mausoleums and climb some high towers. You will be amazed, I promise.
So you love highland? Good news, more than half of Tajikistan is higher than 3000 meters! Go for some incredible hikes and enjoy the hospitality of local people. Even though Tajikistan is not the greenest country, the mountains are absolutely stunning!