How do I automate domain and web host purchases on my site?

I have a WP Multisite install at I want potential clients to be able to purchase hosting packages and domains from my site. I currently have WHMCS and have begun to implement that to my site. But, what would be easier to use? WHMCS or ProSites? I want them to be able to register a unique domain, not a subdomain, and to add this to a new hosting account on my reseller plan. I believe I am on the right path, but after installation of WHMCS, the page that you are brought to after going to is NOT my homepage…it is a login page. I am not sure if I need to edit this in the WHMCS settings or if I did something wrong.

I appreciate any feedback.