copied from some where else...
"Stock, XP, FSX, and P3D all look like crap. With some mods, they can all look great. XPlane is a hell of a lot cheaper to get looking beautiful (cost of base sim, cost of planes, then freeware orthophoto tools)"
my 2p's worth
XP =
X-plane (trial download is available but has no add-ons included), FSX=MS Flight sim 10 (old 32bit and supposedly no longer being developed), p3d =
Lockheed Martin’s Prepar3D® (hide your wallet),
Flight Sim World new boy on the block
comparison
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all depends what sort of flying you want to do , an accurate sim (aerodynamics etc) or a shiny hop on board and away you go. Jet, airbus or biplane, you can also join virtual airlines, re-enact historic flights (Dambusters raid for example)
get a cheap joystick if you haven't got one already, a
Speedlink Black Widow Flightstick is functional and cheap
I'm in the XP camp, I'm still on v10, v11 is out now but lots of free scenery/planes/add-ons available. You can use multiple pcs/monitors to do different functions, ie 1 for view from the cockpit, 1 to display the controls 1 for navigation systems