While decoys can work, don't let it become a crutch for a weak stand set up. I have seen a lot of guys fall into that trap. They expect that a decoy is going to be an end-all-fix-all, but it isn't. You can get very dejected when they don't come running in to a new decoy just because you fired it up. A lot of times they bust you with the wind and they will ignore the decoy all together.
That said, the Mojo Critter sets the bar for a stand alone decoy. It is quiet and easy to use, and I have seen it do wonders with the right stand set up.
I have also had luck with the Whirling woodpecker and the pilleated woodpecker decoys. Could just be that they can see them from farther off since they are up in a tree, but I have had more than one coyote cirle underneath the decoy.