Well, I currently use F1view since my computer can't really sustain the frame rate hit of an extended virtual cabin. What I mainly use it for is taking wing-shots in the planes that still render the wing-surfaces, even with the virtual cockpit disabled, meaning I don't have to worry about walking around that much.
Active camera gives you much more ease in movement (with all it's settings completely adjustable), and really does feel like walking around an environment (rather than simply adjusting a view angle like F1View). I tried out their fully featured demo and deemed that it wasn't worth my money (since i'm not a VC flyer), but I did like what they offered. For one thing, they add a "head latency" effect to the VC, meaning when you're taking off or landing, your head vibrates much like it would as a result of uneven runway surfaces. When you turn the plane (either on the ground, in the air, or during take off rolls), your head takes a second to catch up with the movement. It certainly adds to the "really there" feeling of VC flying. You can also pre-save up to 10 views I believe, extremely handy if you're a VC flyer!
Both are very simple to do a full trial of, so I hope your decision goes well!