I also did allot of research on this same decision. The majority out there are all after speed so they choose the 2-3 degree off-set. If you keep digging and ask some of the more experienced hunters, they all recommend 4 inch long right helical. Reason is faster stability and better arrow flight especially if you will be using broadheads. Many of them with chronographs say that it doesn't reduce speed as many think and the stability and accuracy gained if far better.
As far as brand, I researched and found out that GoldTip is changing to VaneTech fletching in 2006. GoldTip Tech Services states these are better than duravanes offered in previous years. VaneTech vanes are hard to find since most dealers aren't aware that GoldTip in changing over. I found great arrow prices offered with these new vanes at mtnarchery.com
They are based out of Idaho.

Good luck