"This is a great opportunity, because every comic out there is doing commentary on Trump anyway. Here is a chance to do their material and right in front of him. This is an opportunity to do something new."...ADDED: I just assumed it would be Dennis Miller:
Patrick Gavin, director and producer of the 2015 documentary about the event, “Nerd Prom: Inside Washington’s Wildest Week,” said via email that the “reason this is a tough decision for a comedian is because, if they’re too tough on Trump, they run the risk of violating the ‘singe, but not burn’ principle that guides the dinner (they also run the risk of perhaps not getting the gig in the first place). And if they’re too soft — or soft at all — they will suffer the wrath of half of the country that view taking it to Trump as nothing short of a civic requirement.”...
“The choice of comedian could by itself determine whether President Trump comes at all,” Gavin said. “I can’t imagine Trump being interested in taking grief from an edgy comedian and just taking it for an hour.”
IN THE COMMENTS: tcross recommends Susie Essman (of "Curb Your Enthusiasm") and points to this clip, a Friars Club roasting of Trump from 2004. I'm just closing in on 30 seconds near the end, which is interesting because it addresses Trump's gruff game face (which we're so used to now) and because we get to see Trump really laughing (and some people — notably Chuck Todd — have the idea that Trump never laughs)(NSFW):