WWIIOL is one heck of a good tank sim if you don't mind the lack the ground clutter. If you just pretend that you are fighting in the dessert (sans dust) it kind of works.
The WWIIOL FM though leaves a lot to desired though. It has been a bit since I played but used to have a good time lowering the flaps on the ME109 and doing strafing runs at 27mph. Other folks would swear the Stuka was best stall fighter in the game.
The one thing WWIIOL has that this does not is infantry. But, and this is a big "but," city fighting as infantry is pretty much like slugging it out in the mall parking lot. Most of the buildings are locked, there is no cover, and it is more or less you against the tanks.
So, answering this question for air combat only, here is what I think:
AH: Best flight model but damage model does not seem to be there. (Oh come on, we have all flown around furballing in a burning Zeke. Just admit it.)
WB: Best damage model (by far) and the graphics are very good but the FM seems more "tweaked" to the designer's preconceived notions to me. For example the FW190-D9 in WB turns simply horridly, the B-25 on the other hand seems quite nimble.
WWIIOL: Damage model does not seem to exist at all. Lag makes furballs impossible. FM allows more or less infinite E. (The ME109 used to actually gain alt doing loops.)
DoA: I'm also going to toss out "Dawn of Aces" here which is the old Warbirds (2.07?) version but with a very small set of WWI aircraft. Graphics and game play are a bit old fashoned but the FM is wonderful and the community is the best I've ever played with online. (Eh-hem, I of course mean the best community outside those who read this board. Yeah, that's it.)
SDOE: There is also "Screaming Demons Over Europe" with which I have no experience with at all.
For myself, it is all just killing time until "Birds of Prey" is released. (
http://www.wingswithwires.com)
Hope I helped. Glad to have you on board.