They do all look like really good polo wraps!
If your horse doesn't have any leg issues and you're just planning on using the polo wraps for light support and for protection against bumps and knocks that could occur during riding then the Vac's polos would be a good choice, they are just basic fleece polo wraps that would offer protection from knocks and bumps and maybe some light support as well.
If your horse has had an injury in the past, and/or needs a bit more support than the average fleece polo wrap can give, then the Eskadron Climatex polo wraps may be the best choice, I think that they may offer a bit more support than regular fleece polos because of the stretchier more elastic material, but I could be wrong.
The Back on Track polos, would be good choice if your horse has had an injury in the past that would benefit from the ceramic technology that is said to increase circulation and speed up the healing process. I don't think that they would offer any more support than the regular fleece polo wraps though.
I hope this helps you with your decision!