Yep, finding the kind of quality content that matches the niche/theme of your site is the most important thing when you're looking for a content provider.
But what keeps me coming back to a certain provider's site is:
- ease of purchase and delivery. Do they have a tight CC processing and ftp system? or do you have to email back and forth a couple times before they get the order right and then wait 2 weeks for delivery.
- frequency of updates. No point in going back very often if there's nothing new to see.
- samples display. Definitely need to see a few large samples as well as a contact sheet of the whole set.
