Adam Site.Pro markets to everyone including their own standalone builder's pricing/hosting. We've had good pricing for years but I think it's higher these days. What Enhance should try to offer is a plugin where servers are licensed and hosting customers can freely use. That's the only way we handle it. It's a value add for us bundled into our plans.
It's also a bit clumsy and most clients build some of ugliest websites possible unfortunately! No blog feature and rudimentary e-commerce support. We only used it in the early days when it was one of few options with a decent cPanel plugin. SitePad is better but lacks e-commerce features.
My sense of Kopage so far seems much better. It apparently is more like a CMS that presents a website builder like UI. They answered my sales inquiry fast (late Saturday inquiry was answered at 4AM Sunday) and the response was this:
Thanks for your email.
Yes, Kopage would be a great fit. I didn't had a chance to assist any of our partners integrating with Enhance yet, but I'm almost sure our WHMCS plugin will work out-of-box.
You must know it works a bit different than other website builders, Kopage is more a CMS like WordPress, but it looks like a website builder. All website files, including system files and user's data files are stored directly in user's own public_html (or similar) folder, so when you have Kopage plugin for cPanel or WHMCS, it's just copying website files from the source location on y our server to user's own local folder and redirects user there: there's no general URL for website builder, from where user would have to "publish it", all changes are made directly on user's own website.
You can give it a try, you can upload this installation.php file to any test FTP:
It requires PHP 7.1-7.4 or PHP 8.1+, with ionCube Loaders (basically the same requirements as WHMCS itself)
Once setup, it's super easy. Set and forget. Additionally we don't keep your clients' data, it's stored in their own /public_html/data folder, including raw data, you have full control over it in case if you want move websites or to migrate data to another system in the future.
Until Enhance automates Ioncube support it'll require manual installation, but otherwise it should be able to be installed from the WHMCS module to an Enhance website probably via FTP/SFTP. I'll test this later this week if possible.
With cPanel I used several plugins but I prefer to leave Enhance as unencumbered with plugins as possible.