On the GodisOpen facebook page, a conversation is occurring over the resent history of the Open Theism movement. Some are concerned about the prominence of the philosophical wing of Open Theism, wondering who the Biblical Open Theist leaders are.
This chart may provide an answer (to the extent the chart is correct). Morrell, Enyart and Saia seem to be main the contenders, although not as prominent as the Philosophical Open Theists (Hasker, Boyd, Rice, Swinburne, and Oord).
I think the chart is really subjective… :-/