Cutlass RGs are also an undervalued model right now. Most people who want a 172 don't want the higher maintenance costs and complexity of a constant-speed prop and retractable gear. Most people who have "complex aircraft" experience want something larger and faster than a 172. A stone-reliable, high-wing four-seater that cruises at 140 knots is something I personally would love to own.
Although, if we're talking aircraft in general, my dream plane is a Taylor Mini-Imp, “The nearest thing there is to a witch’s broomstick.”