I've never played WW2 online, however I've played AH for over 15 years

and haven't got tired of it. Here's why:
1. The open MA:
The open MA allows you to fight how you want, in any plane you want, whenever you want. It's basically a survival of the fittest and you can roll any plane you dare and fly it how you want. The large map gives you a full scale idea of strategy to win a map rather than a match play scenario which isn't as satisfying, IMO. It's very challenging but also rewarding. You can bomb any enemy base, and don't have to listen to anyone. You can fly with a squad and feel like you are in Black Sheep Tearing up the skies. There are bomber squads, and tank squads you can be apart of if you want. Or create your own! Or go lone wolf. There are no cheesy fly outside the plane modes and no airspawns, and pretty much no rules. I really enjoy this because it's challenging and rewarding and never the same.
2. The special events:
The special events are where you find you your "realism". Fighter Squad Ops, go check out that part of the forum. You can join in with a squad on Friday nights, and it depicts a battle that happened in WW2. It's planes that are Axis Vs Allied and "fairly balanced" per the planes that actually fought in that battle. It's great for wanting those realistic strategy based squad ops where you have a mission assigned to your squad and stick to it. I'd definitely recommend looking into FSO and giving it a try.
The other special event I'd recommend checking out is Combat Challenge, which also has a thread page in the forums, just under Fighter Squad Ops (FSO). It also happens on Friday nights. There is one coming at the end of the month. Combat Challenge is giant furball between axis V allied in balanced plane sets. You get airspawns that bascially put you right into the fight. These are very fun, not so serious and very actionable for jumping right into a fight. I'd highly recommend checking it out.
3. The training
The trainers here are very nice and can help you get going and learn the basics, as well as advanced ACM when you get there. I'd highly recommend setting up a time with a trainer. It will benefit you a lot. There is also a plethora of training videos and materials offline if you search around.
4. Great offline missions.
I actually haven't really played them, however I've heard they are a lot of fun. You jump into them and get right into a big historical battle. Definitely fun for not serious gameplay and can help you learn the game.
5. The flight model and plane choices:
It's a great flight model and planes all have strengths and weaknesses. The games allows you to take off and fly rather than having to press buttons, taxi out, and worry about oil and over heating and all of that. It's a lot less pain in the arse and you can just worry about getting in the air and fighting. There are a ton of planes to choose, and besides the perked ones. You can fly them all without having to "get to the next level". This provides you the opportunity to fly almost all planes right out of the gate and learn what you want.
6. Tanks
While I am not a tanker, there are a lot who play just for the tanking experience on a big map to attack bases and get into tank wars. It's not my thing, I'm a fighter guy, but if you enjoy tanking strategy on a world map, this is a great place for it.
There are a lot of things AH offers that no other game does. The strategy, large Map big team battles and furballs, special events that provide some great realism in battles, and the tons of plane choices to learn and fly are a few of the reasons why I am still around.
Hope yall stick around and learn the game and try some events and different planes
