I really like OpinionX for its ranking options, visual analyses of the results and the possibility to have a bulk import. It's easy to set up, and participants can also use it very easily. There's lots of room for customization, and it really solved our problem with ranking. Other survey systems didn't allow us to set a limited amount of responses and rank them effectively, so this feature in OpinionX stood out for me.
OpinionX helps teams run advanced market research surveys that measure user needs, map customer segments, and model pricing decisions using methods like conjoint surveys, maxdiff analysis, segmentation and clustering.