If they don't have reseller plans listed why are you going to ask?
You better go to a hosting directory and find some companies that have reseller plans, compare them, ask them some questions (any question you want, even if they have the answer on it's pages), do a search for some reviews on this forum and their own support forums, etc...
Basically, you have to consider the price, their technical support, uptime ...
many resellers have the same features with different prices, WHM and CPanel are standard for many of them.
Regards
Oscar