Because you are trying to capture a client base from such a large geographical area then your choice of server location isn't really a concern.
You could in theory go for the cheaper option of USA based hosting or any cheap hosting you can find - but do you really want "cheap" hosting?
If you are serious about your business then you should be serious about your website and it's hosting... Make you decision on research and word of mouth experiences from other clients (beware NOT to use hosting "top sites" as they are generally biased towards either the host of the website or the largest paying advertiser).
In my opinion the most important factors should be:
- Server uptime
- Support
- Scalability
- Price
- Add-on freebies.
With uptime being the most important and freebies being of little importance.