Dave Smiths are really tough to beat. They are as realistic as you can get but are not as packable as the Avian X. The Avian X are also quite heavy though. It all depends on how you are going to use them. If you are running and gunning I would opt for the Avian X. Blind hunting, the Dave Smiths are the way to go.
They are both pricey. I have used both and think they will both work great. I use the Avians and they have held up well. Turkey decoys have come a long way. With these new decoys, I barely call anymore. I let out a few calls to get gobblers attention and once they see the Avian Jake and hen.....its all over. They can't stand that jaker and MUST fight him....every time!!!!