With the release of SSU, most people will be factoring in some AA shooting into their lists. I’m expanding out of the Revised Core set, and looking at the available options. For axis this appears to be Heinrich, Luther or SturmKonig walkers. I’ve discounted the infantry based ones as theoretically a Range 4 unit can be kept at a squares length by the Range 6 ‘copters.

At the moment I’m thinking between double Heinrichs for small games, double Luthers for medium and a SturmKonig for 300pt games. Any opinions ?

You alreay have Lara and the Flaks, which is the best combo in the game to bring down choppers. You don't have to rely solely on walkers to do your AA fighting. A squad of Heavy Recon Grenadiers is also a good investment.

Lara and the flaks are range 4 aren't they, while 'coptors can shoot at range 6 ?

Sure, but it's just a 2 range difference, it's not so drastic as to make the infantry units not great AA options.

Lara also has Assault, which could be used to "ambush" a chopper if you win initiative and hit it before it moves.

Jowimus said:

With Yakov on the other side, surely

I think walkers with AA ability are better. The increase range is a factor. The infantries lesser range means they have to move to get to the target. A unit that moves can't perform a sustained attack and therefore will do less damage. Besides I am an old tanker and vehicles just appeal to me more.

I recommend you get the stats for the units you intend to buy, then play test with proxy models. This is allot cheaper than buying then and seeing what works.
We can give you advise, but every commander has his, or her own stile. Play testing is the only way to truly find what works for you

Jowimus said:

Don't forget that placing Lara into the middle of the board can deter the choppers to the edges. Letting other units pick them off.