it depends on the requirements! VPS can only handle a few websites and the resources are limited!

It also depends on the costs and the number of customers. My Servers only cost me 4x more than a VPS, but have 16GB RAM, 6 x 2.30GHz Processors and more disk than I'll ever resell. So I suppose it's a matter of how many customers you have.
If it makes more sense to have big machines, and I have lots of these, then they are better. Also if you have many of machine A backs up to machine B and B to C, C to D etc, you have your backup solution sorted as well!
I think what I am trying to say is scale, when you can no longer work out of 2 VPSs it's time to move to 2 dedicated servers.

A Virtual Private Server hosting plan is aimed at users who require SSH or root access to the server and users who need a guaranteed amount of RAM and processor speed.

A Dedicated Server Hosting Plan is aimed at customers who not only require SSH access and guaranteed RAM but who do not want to share the server space and processor with any other users.

Asking such questions is like asking something like "a van or a truck?" If you need to transport yourself with some stuff, you do not need any trucks because it will be unreasonable resource waste. The same is in the hosting world.

Hi

I think first you buy any best company reseller hosting and one month use his services if his services his well so you buy vps or dedicated servers hosting but i am sugg dedicated servers.

For business critical operations, going dedicated will be the best choice, but it's of course not something you should consider if your budget doesn't allow it. Look at your financing, and see if your business is growing fast enough to accommodate the knock a dedicated server will put to your pocket.

Depends on your requirements, budget, and your business growth. Consider a dedicated server when you need more resources and have outgrown the VPS.

When you have large resources to be managed and need high security for your site, consider dedicated instead of VPS.

If your company grows you will monitor your site. IF you have big time loads or crashing of the server ... maybe is time to move to a dedicate.
Also you should monitor from time to time the general statistics.
Also is possible to receive mail from the hosting telling you that you consume ... to much of ... and that you should upgrade to a dedicate.

Vps should be my choice,,,It is a good one in starting a good business...