Probably the most important features in an OS are stability and robustness. You are in an Internet business. You do not keep normal 9 A.M. to 5 P.M. working hours like many conventional businesses you know. You are open 24 hours a day. You cannot afford to be offline, because your customers will go shop at another service like yours (unless you have a monopoly). If the OS of your choice crashes every day, first do a little investigation. There might be a simple reason that you can find and fix. However, there are OSes that won't work unless you reboot them twice a day. You don't want to use an OS of this kind, no matter how good the OS's vendor sales department is. Do not follow flush advertisements—follow developers' advice instead.

Generally, people who have used an OS for some time can tell you a lot about its stability. Ask them. Try to find people who are doing similar things to what you are planning to do; they may even be using the same software. There are often compatibility issues to resolve, and you may need to become familiar with patching and compiling your OS.