A story from the California Farm Bureau calculates drought damage estimates by County Agriculture Commissioners. The individual reports linked on this page are interesting.
Looking at unplanted acreage estimates, cotton leads at over 120,000 acres. Wheat is next at just under 70,000 acres. Lettuce, processing tomatoes, and carrots lead the vegetable category at about 20,000 acres each. A number of miscellaneous vegetables and field crops have much smaller unplanted acrage.
It is worth noting that there are some mathematical and data inconsistencies in these estimates. The Kern report has an obvious math error in the way it is estimating yield loss on planted acres, and this is resulting in some large overestimates of $ losses for certain crops (e.g. a $127 million loss on Roses which is 4-5x typical total revenue for a year). The Fresno report details much fewer unplanted acres than the article states. Perhaps, there is an update that wasn't posted. Overall, I think I will go with the $600-700 million revenue loss from the latest UC-Davis projection over the $1.4 billion reported in this article.