I would evaluate them on everything but how technical they are. Questions like the following should spring first into mind:

•      Is there a community (at least a forum)?
•      Is is an active project?
•      Is there a clear documentation?

This will help you better decide how to approach the control without interference of any technical point of view. After this, then you would analyze the control for what it is, and how it can benefit you from a technical standpoint.