Actually i have been to most of the places you mentioned this year.
How long are you planning to go?
If just for a few days i would recommend Singapore. Its a really safe place, easy to get around and you have a great range of different food options there
- kind of a melting pot of south east asia. For more information look at my tripreport:
http://www.flyertalk.com/forum/trip-...-business.html
If you are planning to make a longer trip i would recommend Japan. As soon as you are there its absolutely easy to get around by trip - so its very convenient to visit a few different citys to see the whole range from historic sites like in Kyoto or bustling citylife like in Tokyo - again more information (especially about getting around by train - but also what you can see in one week) in my tripreport:
http://www.flyertalk.com/forum/trip-...rst-japan.html
If you have any further questions just ask.