Wondering which is the best way to increase launch angle with my driver. Increased loft in the head or shaft flex?
Loft angle will always affect launch angle more than anything you can do with shaft flex. Increase the loft and the launch angle will increase. Increase shaft flex, or go to a lower bend point shaft and the launch angle may increase, but we have seen that this is not always the case. If you are considering going from an S flex to an R flex, the variation in launch may be almost unnoticeable. If you are going from an X flex to an A flex, which is highly unlikely I suspect, you would see some trajectory difference. It takes a lot of variation in the flex profile of shafts to greatly influence trajectory. With loft, you can see the affect with as little as a 1 degree increase. You may need more than that, but you should see a launch angle difference with as little as a 1 degree increase.