I really like Accusim aircrafts. I just like flying an in-depth aircraft simulation. Most of my hours in Black Shark were non-combat. Just setup a mission without any threats, set waypoints, and navigate :)
I fly warbirds in FSX just as they are now - flying and taking care about a plane. Accusim planes have cumulative airframe and engine hours. You have to constantly check manifold pressure, temperatures, rpm, pressures, etc. In each session you start the same plane you've left in previous one. It's an alive plane, and no other sim gives me that.