Something with a noir mystery feel to it, whether that be Lovecraftian horror, Dresden-esque magic mystery, or a straight-up urban crime drama. (Kind of a cop out answer since I'm not saying any game in particular...)
And they have to do Vampire: The Masquerade sometime, right?
We all know Totalbiscuit is a super busy guy dealing with work life AND cancer, but I'd love to see him back for anything at least once.
I don't watch any of CinammonToastKen's actual content, but he seems to have a good rapport with JP and a decent mind for some fun roleplay. I've also seen him do boardgames with the Co-Optional gang.
Danny O'Dwyer? That connection seems a bit obvious considering him and JP already know each other.
I hear Jim Sterling RPs. Every once in a blue moon I stumble across some of his content - he's got a quick wit and... particular sense of humor.
*Oh! Anna Prosser and Nadja sometime, right? (Anna was on once for that charity show ages ago.)