I guess .biz if I had to choose. However, I would never build a company around any of those extensions in the first place. None of them carry much credibility.
I'm not sure what to think about the .asia just now (could be a sleeping giant ??)
...but other than that I would go with .eu if it makes sense and is related to the topic, ie: cruise.eu and not jamaica.eu :bah:
Failing that, I would find another keyword to use in .com or country extension
Really depends on the domain name, website to be developed, etc. For some of my domains I pick the .info ahead of .com's if it's going to be a strong information site while others I go with the .com.au if I'm targetting it mainly at my country (Australia). I also have some .ws domains if I couldn't register my desired keyword in other extensions and they do quite nicely when developed and promoted. I would only pick .asia or .eu if I was targetting them geographic areas with the website.
If you're going to be developing a unique site, then you don't really *need* the keyword and it isn't worth setting up on a fairly unknown extension just because your keyword isn't available on the main ones; do you not have the option to come up with a unique/brandable name? Something clever in .com is always better than keyword.unknownextension.