I have done what I feel is a pretty extensive comparison of most of the sims...
http://www.rcmagazine.net/index.php?...rec/002/rcsims

the long and the short of it is that G2 really is the best out there that I've tried (only possible contender right now that I haven't tried is the AeroFly Pro), the one big drawback is the Price (the other feature I'd like to see it have is the break apart on crash or high G turns, wich is something aerofly Pro supposedly has). the Add-ons REALLY make G2 better, the added fields and planes really make it a much more well rounded program. I still wish that RealFlight would consider a download based method of doing add-ons (with you paying for only the planes you want), but the current method does work so I doubt they'll change it.

If you're on a budget I'd recommend easyfly with the Game Commander... it's pretty reasonable at $30-$50 from www.quantummodels.com and you can use the Game Commander joystick with other sims (like FMS or even realflight which you might be able to pick up cheaper as CD only on ebay or the boards).