Prop planes - Joseph Binka's Beriev be-103
Helicopters - UKMIL's Westland merlin
Military - Bowe Tyson's SU-34 or Tim "piglet" Conrad's OV-10 Bronco
Each relatively simple to fly normally, but doing things out of the ordinary...flying backwards and sideways in the chopper, landing in a marina in the beriev, doing aerobatics in the Bronc(hard but fun when the engines can hold the plane in a near hover and the wings stall easily

)...presents a challenge
Can't wait to upgrade to fsx and do all this on a moving carrier