Just get what you like best. Speculating on which one is going to be worth more later is senseless. Look at X-men LE, everyone thought the Wolverine's were going to sell for more than Magneto's. And let's not mention the speculators that bought one just to flip or thought they could cash in later. Those NIB's sitting in personal collections that you see going up for sale show that people were trying to cash in (why else buy and let it sit NIB for months?)
If Avengers ends up like X-men (code is not well received), it won't matter which machine you have, they'll all be worth less than what you paid. If you buy the one YOU LIKE, then it won't matter as much because it's the one you like.