In a recent article in Southeast Farm Press, Dr. Stanley Culpepper, University of Georgia Extension weed specialist, shared his data on crop sensitivity (visual injury) to dicamba and 2,4-D. Note that most of this data is from trials in Georgia (and some of the crops on the list reflect that).
2,4-D Visual Sensitivity Scale for GA - 2017
(Herbicide rate of visually detectable injury in brackets following sensitivity level)
Lower (>1/75X): Broccoli, cabbage, kale, mustard, onions, turnip
Moderate (1/75-1/300X): Cantaloupe, canola, cucumber, peach, peanut, pecan, squash
Severe (1/300-1/800X): Pepper, tomato, watermelon
Extreme <1/800X): Cotton, grapes, sweet potato, tobacco
For relative comparison, tomato, squash, and watermelon response to Roundup would be in the "lower category"