Pretty much anyone and everyone mentioned in this thread. They're almost all pretty interesting characters, so it would be nice to hear from as many people as possible. My only hesitation comes with certain developers: the ones that aren't very good at letting loose, and are really only there to say a few vague sentences about their game.
There has been a Talkradar/GB cross-over only once twice (Talkradars 30 and 36? Years ago...) and even though it's not around anymore, I'd like to hear someone either from ex-Talkradar or RadioRadar. Henry Gilbert (GR), Chris Antista or Brett Elston (CapCommunity guys) would be awesome. Granted, there's a distinct difference in feel between the Bombcast and anything produced by GR, but I see a bunch of potential here. Besides, Ducktales Remastered is coming out - that's a legitimate excuse to get those guys on?
Also, Brian Ekberg. Outside of Vinny, my second favorite person to ever grace GB/GS.