As I’ve said before, if you have more than a couple of domains reseller hosting is much better than standard shared hosting. Here’s another reason: you can reduce your logins.
The cPanel reseller password, the same one used to login to WHM, serves as a sort of master password. When logging in to any of your cPanel accounts you may gain access using the reseller password. This is a useful feature, as it saves you having to remember all the client account passwords.
If you have a VPS (Virtual Private Server) or dedicated server, you may also use the root password for the same purpose, though I prefer to use the reseller password and save use of root for when it’s truly needed.