I have the stock shaft from the Cobra Fly Z+ in my F7. I get the best launch conditions, as the stock shaft from the F7 is just too low launching for me.
I've experimented with a few different driver shafts and have switched adapters on stock shafts to fit other manufacturers. Pretty interesting when I got fit the fella basically said that there were 2 stock options and one would be better than the other and then simply said, "or you can go boutique." I'd bet of all of the players that would self-identify as a "golfer" nearly 99% play a stock option.
I've been considering something new and want to go hit my head on a bunch of shafts on a monitor sometime soon. Live in a small market so it means travelling.
I will typically buy a shaft. Usually after research and once I can find it for a decent price on eBay. Lately it has been mostly fujikura. Although I did pick up a UST Helium the other week and waiting to put that into something soon
Using a non-stock shaft in my driver for past 2 years, bought it from a chap who had like 7 high-end shafts that he was evaluating and price was a steal. Purchased without testing it out but the specs were close to my previous non-stock (same manufacturer) so thought I would give it a whim. I love the shaft as long as I don't go after it otherwise duck hooker.
Diamana Kai'li 60 X-Flex in my G400. I was fit for the shaft 4 years ago and then told I couldn't find better, even with a new driver head, during my fitting a few weeks ago.
The driver I'm playing now has the stock shaft in it and it's likely the first stock shaft I've played for many years. I can probably count on one hand the number of OEM drivers I've gamed. I normally build my own clubs, but after a bit of research, I decided to give this Fuji Speeder 757 Stiff in the TM Burner TP (2007) I found on eBay a shot and it has performed acceptably so far.
I've been known to buy drivers on ebay and yank the stock shaft without ever hitting it. Gotta have a handful of unhit stock shafts around here, still.
My driver shaft is non-stock, also bought off ebay. Was never fitted, process of elimination has led me to kinda figure what will work. Still lucky that it suits me so well though.
The Kuro Kage Black TiNi 50 was a no cost upgrade to my GBB, recommended by the fitter due to my swing speed (then 97-98 and pushing 60) and the extra kick in the tip. Has proven to be a good choice.
Rogue Max in my 3W was the best of the no-cost options I hit.
I play a non-stock shaft. I have tried several different shafts and always end up back to the one I am using. I just really like the feel and results I get with it. I'm sure there's something better for me. One day I'll get fit and be sure I have the right shaft for me.