What are you planning on hosting on Dedicated server?
1) Server Close to customer, if there are images/videos that need to be loaded quickly
2) You can also use CDN or similar services to speed up load times
3) If customers are US based, choosing central zone, might be a good idea, to serve US west and east coast at same performance.
It mainly depends upon your targeted audience. If you are targeting the global audience then you should choose a famous and well spread datacenter like US as they will be having the best bandwidth carriers. If you are concentrating the business audience in your country only then finding the closest yet reliable datacenter would work for you. As this would help to reach the website quickly taking the advantage of geographic location.