First, I’d like to thank you for grouping philosophers with other famous figures.
Most of Nietzsche’s posts would be helpful and erudite (he was apparently very gentle in person), but we’d have to ban him from all religious topics lest he let loose with endless—though still erudite—personal attacks and flame-bait.
Hobbes would think that @augustlan didn’t have enough power. Every time he answered a new question, his first remark would be controversial and extreme. When asked for clarification, however, he’d walk it back to something that seems pretty sensible (even if rather paranoid).
Hume would basically be like me, but nicer, smarter, and way funnier (so maybe not much like me after all). While Thomas Reid would try trolling him at every opportunity, Hume would keep coming up with jovial ways to put him off. He’d also go out of his way to explain how everyone who disagreed with him was quite clever (even if blatantly wrong).