Customer service is the best in the business. Knowledgeable, attentive — they actually follow-up on issues.
A CMS that's usable for clients but accessible enough for genuine design.
Content management portal and communications system is a step in the right direction for gathering and storing client data.
Licensing that's assigned to the client, not the reseller.
No surprise up-sells or add-ons after contracting.
Fast page loads.
Default responsive settings are impeccable (superior to any other product I've tested); very few overrides needed (if you ever designed a responsive site in Muse, this will make you cry tears of relief).
Auto-subdomains with SSL (reflects well on the white label).
No dislikes, only some ideas for future functionality (i.e. customer data field customization, far more templates, interface for background images, save on HTML, ability to customize white label portal without bothering support, master pages, improved template embed for agencies, web accessibility options).
After trying many major proprietary white label solutions, SiteJet is by far the most outstanding. Highly recommended.
Since custom coding is out of scope for most of my market, the biggest problem was finding a reliable provider that not only hosted a CMS easy enough for clients to use, but that was also sophisticated enough to use best practice design and tech elements. SEO, page load speeds, and other critical elements allowed me to finally create packages that I feel confident selling.