One of the very first things that you should check out while choosing your provider is how their network quality is and how the network response to ICMP Ping requests are. Since a bad network will reflect poorly in your own reputation, this is especially true for reseller hosting ventures.
In a reseller hosting environment, customers trust you with their website data and expect you to keep it running smoothly, without any issues and expect you to at least have 99.99% uptime, the standard in the industry. However, your reseller hosting company is bound to crumble if the very network you host it on turns out to be non efficient and latencious . The network is the key soul of anything related to web hosting, the same goes for reseller hosting. So when picking your provider, you should test with utmost care.
Good gauges of quality are the ICMP Ping test, speedtests from their server and so on. If a speedtest isnft available, create a support ticket asking for one. This will also allow you to gauge their support teamfs quality without any extra effort.