For me the first place would be any or all of the countries bordering Iguazu Falls in South America. Since I live in Italy and have a home in Colorado in the US, I've already seen a lot of Europe, North America and the Caribbean, but have never been to South America although I've been close enough to see the coast of Venezuela. I particularly like waterfalls and Iguazu looks spectacular.
I would also like to visit the tiger temple Wat Pa Luang Ta Bua in Thailand, and the Fiordland National Park in New Zealand
1. Japan - I finally booked a tour and hopefully will be there in July :-)
2. The Azores and Florida. That's for research purposes because I'm interested in civilian air travel of the 1930s/40s and the Pan Am archives are in Florida. And the Azores, that's where transatlantic flights used to stop.
3. North Korea. Last time, we didn't get to see the Kumsungsan memorial palace (which was closed to tourists in 2012) and the Friendship Exhibition (a road had been flooded, so we couldn't get there).
1. Bangladesh ( Sunderban, Cox's Bazar)
2. Tiger temple, Thailand
3. Maldives
very difficult to choose the answer and if you have already seen some, you may feel later that other places is better.