The whiplash decoy is by far the best. In the group that I hunt with we have 4 different brands of pull string decoys, including one made by Aero and one made by whipsplash.
We have had 2 problems with the Aero decoy and both have to do with the way the wing attaches to the body. The wings have a tendency to fall off. That is why they advise you to seal at least 6 holes in each wing, so they float. After 1.5 seasons of use the glue for the coupler that holds one of the wings on has come off. Both are repairable problems but not in the field. If you choose this decoy put a twist in the band to increase tension, so that as you look at it there is an X between where it attaches to the wings and the body. I noticed that the new decoys that Aero is putting out have the black on the wing as paint. The older version on mine have black flocking on the wing which tend to not look as good when they freeze.
The whipsplash takes 1/4 the effort to pull and spin 2x as fast as any other decoy I have used. Also the length of pull seems about 2x as long. The wings securely attach with set screws and are much larger. We only hunted over this decoy 3/4 of last season but have not had a single problem. It is a very high quality piece of equipment. The one minor change I would make is that post that it mounts on is 1/2 inch, I prefer 3/4. But I would buy another on in a heartbeat.
So long story short go for the whipsplash
Good luck with your decision, you have a couple months