If you are going to go Dexron VI, then any Dexron VI will do. GM does not allow much variation from one brand to another. Valvoline is the only one that says they are full synthetic, so I might choose them over the others, but they will all be pretty good.

My decision to go with Redline D4ATF was based on many other people using it with good results in their A5S390R transmission. I have not seen many reports of people going with a Dexron VI for that transmission, and I wanted to see more reports of good results with it in that transmission before I made the switch myself.

Let us know what you decide and how it works out.