My observation is you get what you pay for (which is nothing in the case of free sims). When I started flying, I used a Reflex XTR sim. Basically I got the usb adapter for my radio from EBay along with the software cd which was not original. It was good enough for learning the Trainer. When I moved to a Tiger I tried the closest thing to that on the sim but it was not the same airplane. Then when I got a Topstar (Flip3D), I tried that on the sim and it was not the same either.

Finally I gave up and bought the RF5. Since it has a lot of options with engines, airplanes and infinite customisation, you can setup the airplane the way you want. You can make the airplane difficult to fly by onderpowering it or whatever. For example, I fly the Reactor 46 now and on the RF5 there is the Reactor 50cc. They dont behave the same but are similar. I configured the Reactor50cc on sim with a 120AX making it underpowered and quite difficult to fly. That ensures that I fly the Reactor 46 on the field (With a 55AX) a bit more conservatively. But you wont get a similar airplane and options on any other sim though

Ameyam