Pretty much any joystick will work with FS... in the sense that FS can read input from any game controller plugged into your pc... but for starters, i think what you'll want is a 4 axis joystick with a good number of buttons... (4 axis is left-right, up-down, rudder twist and throttle), but trust me, once you get addicted, there's no turning back
i have 6-7 joysticks pling up in my room so far... and i'm still unsatisfied... my latest was a Clone Cobra stick (kinda generic) with 4 axis - 12 buttons... i used it until it broke down on me... now i'm back to my 9-year-old sidewinder FFB 1.0 which seems to be indestructable... (hehe i've dropped it so many times it should be in pieces now)
my next joystick will be the Saitek X52 Pro, coupled with their Pro Flight Rudder Pedals... these i suspect will make me quite satisfied for at least my helicopter/fighter/spaceship needs
then there will be a yoke... but let's not get into that right now as i could go on forever...

Cheers
HarvesteR