3D Hubs offer a comprehensive review of currently available 3D printers.
Check their 3D Printer Guide before you decide which machine to choose for your workshops. They surveyed the global community of 3D printing service providers to learn from their experiences.
The review investigated the following parameters to help measure the user experience of a range of 3D printers: print quality, build quality, reliability, ease of use, print failure rate, customer service, community, running cost, software, and value.
Certainly only a selection of printers is featured in the Guide but the list provides a good starting point for further explorations.