What are your favorite idea groups?

To clarify, I don't care what we all know are the best. Administrative is a must for world conquests, yes. Quantity is amazing, of course.

But what do you like, dear player? Which idea groups simply tickle your fancy? They could be good or bad, niche or broad, I just want to hear your honest thoughts.

Personally, I loved Espionage even before it got buffed. Something about it has always felt so... slick. Plus I love being an underhanded plague on the AI.