My vote is defiantly AA50, it can cover all players experience from first timer to master. The system is the stepping stone to G40, and some G40 rules can be house ruled into AA50 pretty easy. Tech is also the best, even if you tone it down a bit.
We are playing AA50 now for the first time in over a year (maybe 2). I bought and we played a couple games of the new 1942 II over last weekend. It was cool, but we thought why play the poor mans version when I have AA50. So in a way the 1942 II has re-sparked our interest in Anniversary. We are now in our 2nd game with tech (AA50 1942 set-up). We have tweaked a few things (borrowed from G40) like a straight rule, BB’s repair beginning of your next turn, tanks at 6 IPCs, and the new rules for AA guns. We are having a great time and will continue down this path for some time. It is a refreshing change from G40.
I think what I like the best is there are 2 set-ups in the same box for AA50. I would love if G40 came with a 1941 set-up in the reprint. I have played Oztea’s 41 set-up for global a couple times and to his credit it was quite cool. I think he may have went a little overboard with units in the set-up though (the box is nearly empty once you set-up LOL).