What factors do you consider when you are finding a new server? I assume that performance, durability and cost efficiency are the main factors to consider. What else?
Along with the characteristics you mention, I'd have to include compatibility with whatever else I already have in place: equipment, tools, expertise, infrastructure, software, procedures...
In addition to that, data safety is one of the most important factor to consider when finding a new server. Though the server is good at performance, but if the server is not full proof and secure, all the efforts you have put in to your website will be of no use.
eUK-Mac has hit the nail on the head. Data safety is one of the most important things we need to consider in today’s environment. The other issue, which we consider very important, is compatibility as we have a number of different servers with people trained on the operating of those servers.
You want to see if you can get as much as you can, with a server that will take up as little space as possible. You will also need to know what you actually need in a server, so that you don't sell yourself short.
I would vote durability. I would almost pay more for something that's more durable than anything else. I don't want to get notifications from hours ago saying something went down while I was away.
Also, CPU is one of the most important elements of a server. It is a heart of any computer system. Currently, there are many processors options are available in the market to choose. However, to get the best, you need to understand the technologies present in the processor. Your server performance depends on the CPU as well.
Besides how well the server performs, durability and not costing too much, I think the most importent thing you should look for is data security. You also want to make sure the server is compatible with everything else you have, that way you do not have to rehaul everything.
I check to see what I am getting for the money that I am paying. There are too many "deals" out there. Cheapest is not necessarily always the best. Figure out what it is that you know you will need, and make sure you get all of that. Don't sacrifice on something you will really need.