You first question should be what operating system your server will be based on. We feel it is more robust, and easier to setup. Next will be what kind of hardware you get for your server. A more technical question, but very important, is whether your server is placed on a dedicated port, or on a shared port. A related question is whether the network you are connected into is based on a switch or a hub.
Switched networks are higher performance, and offer more security.
Hurricane Electric places servers on their own dedicated 10Mb or 100Mb port, on their switched network. Make sure you ask if those figures relate to their network, or the network of their provider. Finally, the most important network question, how much of your network is utilized. The speed of the network will suffer because of congestion. Hurricane Electric prides itself on performance.