There have been quite a few decent ones over the years. A lot depends on what you want to do with them. I used to play European Air War for years. At the time, it (IMO) had superior/more realistic aircraft handling than its peers -- at that point probably CFS1/CFS2. The Microsoft terrain texturing was far better though.
From a pilot/combat perspective, IL-2 is pretty accurate with the realism settings on their highest. Downside (again IMO) is that you're stuck with the Eastern Front scenarios. The later add-ons did allow Pacific Theatre combat, etc. The flight model is the excellent on all of the versions.
My personal favorite insofar as an accurate/realistic sim of a WW2 airplane is the Hurricane add-on developed for MS Flight Sim 2004. I can't remember who created it but everything works as it should and ham-fisted pilots will be rewarded by very accurate stalls/spins. It's only downside is that there are no operable weapons. I've had discussions with Ray Scott, who flies the Fighter Factory Hurricane, and the handling quirks and traits I mentioned from the sim are the same on the real aircraft.
Storms of War has been in development for years and appears beset by an unending string of problems and release delays. I think the original release was supposed to be in 2005.