On Saturday, 1 October 2016 21:54:39 UTC+3, Jonathan St. Cloud wrote:
Just wondering what happened to the Quintus and Antares 23 in the open class competitions around the globe. At the WGC in Uvalde both the Quintus and Antares were highly anticipated, with a pilot flying the Quintus winning the contest. Now the JS-1 at 21 meters seems to be the glider if you are going to race open class and want to win. Is it money, convenience or performance? I rarely see even an EB-29 in the open class competitions. What is the best open class glider and why?

If you mean one you can buy, my (and many others') guess is EB29R. It has latest wing profiles and aerodynamics, combined with large span and still very high wingloading (for those who need it). It most likely have an edge in low speeds/thermalling/best ld, and looses nothing at high speeds.