Aces Over The Pacific by Dynamix
QFT. Same with Aces Over Europe [same exact engine]. You see a lot of the same advanced settings from those games carried over all the way to MCFS and IL2. They literally paved the way.
I'd also throw Red Baron 3d up there. The first Red Baron was also made by Dynamix, and the second one (later upgraded to Red Baron 3D) added even more. Nothing quite like turning too hard and having your lower wing snap off...