Its been my experience that they all work about the same, I'm really sure there are better ones out there but I doubt you will notice a ton of difference. Plus you can use multiple socks to acheive ideal drift. Some people even use 5 gallon buckets as drift socks so there cant be a ton of difference in them all.
Zman-Just make sure it has a release rope-thats the rope that goes to the center of the drift sock and collapses the parachute. Otherwise, its REAL hard to pull it back into the boat of you got a good wind. : Ed